We are trying unbound out. Machine is quad CPU with 16GB ram. I'm picking on thread 2 because it shows the issue best as it seems to receive up to 6 times as many queries as the other 3 threads. As you can see, the time to execute climbs gradually through the period and starts to "exceed" allowed limits about mid-way down the stats results shown here. Config bits. server: verbosity: 1 statistics-interval: 300 statistics-cumulative: yes extended-statistics: no num-threads: 4 outgoing-range: 2048 msg-cache-size: 3G msg-cache-slabs: 8 num-queries-per-thread: 2048 jostle-timeout: 1000 so-rcvbuf: 8M rrset-cache-size: 6G rrset-cache-slabs: 8 cache-min-ttl: 7776000 harden-glue: yes harden-dnssec-stripped: yes harden-referral-path: yes use-caps-for-id: yes unwanted-reply-threshold: 10000000 val-clean-additional: yes val-permissive-mode: no key-cache-slabs: 8 neg-cache-size: 1g Below are snippets from the statistics taken roughly every 5 minutes from startup over a period of 7 hours. server stats for thread 2: 420 queries, 284 answers from cache, 136 recursions server stats for thread 2: requestlist max 21 avg 16.2647 exceeded 0 server stats for thread 2: 3189 queries, 3053 answers from cache, 136 recursions server stats for thread 2: requestlist max 21 avg 16.2647 exceeded 0 server stats for thread 2: 3375 queries, 3239 answers from cache, 136 recursions server stats for thread 2: requestlist max 21 avg 16.2647 exceeded 0 server stats for thread 2: 4560 queries, 4424 answers from cache, 136 recursions server stats for thread 2: requestlist max 21 avg 16.2647 exceeded 0 server stats for thread 2: 32129 queries, 13211 answers from cache, 18918 recursions server stats for thread 2: requestlist max 1196 avg 620.017 exceeded 0 server stats for thread 2: 227635 queries, 63600 answers from cache, 164035 recursions server stats for thread 2: requestlist max 1196 avg 605.375 exceeded 0 server stats for thread 2: 412374 queries, 113701 answers from cache, 298673 recursions server stats for thread 2: requestlist max 1196 avg 649.591 exceeded 0 server stats for thread 2: 591627 queries, 164560 answers from cache, 427067 recursions server stats for thread 2: requestlist max 1196 avg 685.99 exceeded 0 server stats for thread 2: 762418 queries, 214876 answers from cache, 547542 recursions server stats for thread 2: requestlist max 1196 avg 725.279 exceeded 0 server stats for thread 2: 925072 queries, 265281 answers from cache, 659791 recursions server stats for thread 2: requestlist max 1196 avg 766.182 exceeded 0 server stats for thread 2: 1082217 queries, 315509 answers from cache, 766708 recursions server stats for thread 2: requestlist max 1213 avg 803.033 exceeded 0 server stats for thread 2: 1240514 queries, 367629 answers from cache, 872885 recursions server stats for thread 2: requestlist max 1336 avg 841.245 exceeded 0 server stats for thread 2: 1399258 queries, 421640 answers from cache, 977618 recursions server stats for thread 2: requestlist max 1360 avg 874.701 exceeded 0 server stats for thread 2: 1555372 queries, 476520 answers from cache, 1078852 recursions server stats for thread 2: requestlist max 1390 avg 908.038 exceeded 0 server stats for thread 2: 1714148 queries, 534429 answers from cache, 1179719 recursions server stats for thread 2: requestlist max 1478 avg 942.845 exceeded 0 server stats for thread 2: 1877100 queries, 595948 answers from cache, 1281152 recursions server stats for thread 2: requestlist max 1603 avg 977.634 exceeded 0 server stats for thread 2: 2046507 queries, 661158 answers from cache, 1385349 recursions server stats for thread 2: requestlist max 1661 avg 1018.34 exceeded 0 server stats for thread 2: 2230528 queries, 734070 answers from cache, 1496458 recursions server stats for thread 2: requestlist max 1792 avg 1063.32 exceeded 0 server stats for thread 2: 2420948 queries, 811552 answers from cache, 1609396 recursions server stats for thread 2: requestlist max 1876 avg 1106.96 exceeded 0 server stats for thread 2: 2627825 queries, 898335 answers from cache, 1729490 recursions server stats for thread 2: requestlist max 1948 avg 1152.9 exceeded 0 server stats for thread 2: 2847864 queries, 993012 answers from cache, 1854852 recursions server stats for thread 2: requestlist max 2010 avg 1198.99 exceeded 0 server stats for thread 2: 3075730 queries, 1093945 answers from cache, 1981785 recursions server stats for thread 2: requestlist max 2088 avg 1244.61 exceeded 0 server stats for thread 2: 3320791 queries, 1204754 answers from cache, 2116037 recursions server stats for thread 2: requestlist max 2129 avg 1289.26 exceeded 0 server stats for thread 2: 3593773 queries, 1329840 answers from cache, 2263933 recursions server stats for thread 2: requestlist max 2129 avg 1333.68 exceeded 0 server stats for thread 2: 3877901 queries, 1462415 answers from cache, 2415486 recursions server stats for thread 2: requestlist max 2340 avg 1381.81 exceeded 0 server stats for thread 2: 4169522 queries, 1601187 answers from cache, 2568335 recursions server stats for thread 2: requestlist max 2340 avg 1424.49 exceeded 0 server stats for thread 2: 4458010 queries, 1741370 answers from cache, 2716640 recursions server stats for thread 2: requestlist max 2340 avg 1461.19 exceeded 0 server stats for thread 2: 4755954 queries, 1887372 answers from cache, 2868582 recursions server stats for thread 2: requestlist max 2340 avg 1497.73 exceeded 0 server stats for thread 2: 5054311 queries, 2035933 answers from cache, 3018378 recursions server stats for thread 2: requestlist max 2392 avg 1534.58 exceeded 0 server stats for thread 2: 5362834 queries, 2191665 answers from cache, 3171169 recursions server stats for thread 2: requestlist max 2438 avg 1571.12 exceeded 0 server stats for thread 2: 5669256 queries, 2347984 answers from cache, 3321272 recursions server stats for thread 2: requestlist max 2463 avg 1604.42 exceeded 0 server stats for thread 2: 5975214 queries, 2506445 answers from cache, 3468769 recursions server stats for thread 2: requestlist max 2463 avg 1635.18 exceeded 0 server stats for thread 2: 6279369 queries, 2665381 answers from cache, 3613988 recursions server stats for thread 2: requestlist max 2591 avg 1664.99 exceeded 0 server stats for thread 2: 6577860 queries, 2822890 answers from cache, 3754970 recursions server stats for thread 2: requestlist max 2591 avg 1691.34 exceeded 0 server stats for thread 2: 6879207 queries, 2983199 answers from cache, 3896008 recursions server stats for thread 2: requestlist max 2591 avg 1717.35 exceeded 0 server stats for thread 2: 7175981 queries, 3141895 answers from cache, 4034086 recursions server stats for thread 2: requestlist max 2607 avg 1744.31 exceeded 0 server stats for thread 2: 7468573 queries, 3300361 answers from cache, 4168212 recursions server stats for thread 2: requestlist max 2607 avg 1768.51 exceeded 0 server stats for thread 2: 7763213 queries, 3459687 answers from cache, 4303526 recursions server stats for thread 2: requestlist max 2615 avg 1792.17 exceeded 275 server stats for thread 2: 8049494 queries, 3615698 answers from cache, 4433796 recursions server stats for thread 2: requestlist max 2649 avg 1814.33 exceeded 391 server stats for thread 2: 8339874 queries, 3771948 answers from cache, 4567926 recursions server stats for thread 2: requestlist max 2673 avg 1836.72 exceeded 9291 server stats for thread 2: 8675486 queries, 3928361 answers from cache, 4747125 recursions server stats for thread 2: requestlist max 2673 avg 1865.03 exceeded 79527 server stats for thread 2: 9013544 queries, 4065706 answers from cache, 4947838 recursions server stats for thread 2: requestlist max 2673 avg 1894.08 exceeded 197196 server stats for thread 2: 9325951 queries, 4184820 answers from cache, 5141131 recursions server stats for thread 2: requestlist max 2673 avg 1919.66 exceeded 320054 server stats for thread 2: 9649570 queries, 4311387 answers from cache, 5338183 recursions server stats for thread 2: requestlist max 2673 avg 1943.58 exceeded 442555 server stats for thread 2: 9883086 queries, 4386420 answers from cache, 5496666 recursions server stats for thread 2: requestlist max 2673 avg 1961.76 exceeded 567156 server stats for thread 2: 10187789 queries, 4502652 answers from cache, 5685137 recursions server stats for thread 2: requestlist max 2673 avg 1982.28 exceeded 690181 server stats for thread 2: 10527437 queries, 4638576 answers from cache, 5888861 recursions server stats for thread 2: requestlist max 2673 avg 2002.7 exceeded 818783 server stats for thread 2: 10845189 queries, 4760934 answers from cache, 6084255 recursions server stats for thread 2: requestlist max 2673 avg 2020.86 exceeded 946745 server stats for thread 2: 11084550 queries, 4838916 answers from cache, 6245634 recursions server stats for thread 2: requestlist max 2673 avg 2034.8 exceeded 1073714 server stats for thread 2: 11402798 queries, 4959856 answers from cache, 6442942 recursions server stats for thread 2: requestlist max 2673 avg 2051.26 exceeded 1202308 server stats for thread 2: 11722778 queries, 5082975 answers from cache, 6639803 recursions server stats for thread 2: requestlist max 2673 avg 2066.72 exceeded 1330516 server stats for thread 2: 11993865 queries, 5179640 answers from cache, 6814225 recursions server stats for thread 2: requestlist max 2673 avg 2079.3 exceeded 1457073 server stats for thread 2: 12286524 queries, 5286754 answers from cache, 6999770 recursions server stats for thread 2: requestlist max 2673 avg 2091.88 exceeded 1588787 server stats for thread 2: 12569883 queries, 5390261 answers from cache, 7179622 recursions server stats for thread 2: requestlist max 2673 avg 2103.54 exceeded 1717405 server stats for thread 2: 12833143 queries, 5480857 answers from cache, 7352286 recursions server stats for thread 2: requestlist max 2673 avg 2114.34 exceeded 1848543 server stats for thread 2: 13088804 queries, 5566827 answers from cache, 7521977 recursions server stats for thread 2: requestlist max 2673 avg 2124.56 exceeded 1979982 server stats for thread 2: 13339028 queries, 5649428 answers from cache, 7689600 recursions server stats for thread 2: requestlist max 2673 avg 2134.2 exceeded 2112551 server stats for thread 2: 13589261 queries, 5731389 answers from cache, 7857872 recursions server stats for thread 2: requestlist max 2673 avg 2143.23 exceeded 2246431 server stats for thread 2: 13831526 queries, 5809218 answers from cache, 8022308 recursions server stats for thread 2: requestlist max 2673 avg 2151.68 exceeded 2380025 server stats for thread 2: 14074045 queries, 5885578 answers from cache, 8188467 recursions server stats for thread 2: requestlist max 2673 avg 2159.78 exceeded 2517341 server stats for thread 2: 14310994 queries, 5958194 answers from cache, 8352800 recursions server stats for thread 2: requestlist max 2673 avg 2167.59 exceeded 2656417 server stats for thread 2: 14542656 queries, 6028031 answers from cache, 8514625 recursions server stats for thread 2: requestlist max 2673 avg 2174.91 exceeded 2795338 server stats for thread 2: 14768848 queries, 6093829 answers from cache, 8675019 recursions server stats for thread 2: requestlist max 2673 avg 2181.93 exceeded 2936464 server stats for thread 2: 14993464 queries, 6158626 answers from cache, 8834838 recursions server stats for thread 2: requestlist max 2673 avg 2188.48 exceeded 3079132 server stats for thread 2: 15216858 queries, 6222283 answers from cache, 8994575 recursions server stats for thread 2: requestlist max 2673 avg 2194.84 exceeded 3222538 server stats for thread 2: 15440568 queries, 6282954 answers from cache, 9157614 recursions server stats for thread 2: requestlist max 2673 avg 2201.12 exceeded 3372315 server stats for thread 2: 15663324 queries, 6344440 answers from cache, 9318884 recursions server stats for thread 2: requestlist max 2673 avg 2207.11 exceeded 3520766 server stats for thread 2: 15888324 queries, 6406005 answers from cache, 9482319 recursions server stats for thread 2: requestlist max 2673 avg 2212.97 exceeded 3671367 server stats for thread 2: 16110454 queries, 6465240 answers from cache, 9645214 recursions server stats for thread 2: requestlist max 2673 avg 2218.59 exceeded 3824213 server stats for thread 2: 16332045 queries, 6523675 answers from cache, 9808370 recursions server stats for thread 2: requestlist max 2673 avg 2224.04 exceeded 3978297 server stats for thread 2: 16552213 queries, 6581148 answers from cache, 9971065 recursions server stats for thread 2: requestlist max 2673 avg 2229.27 exceeded 4132981 server stats for thread 2: 16772511 queries, 6639153 answers from cache, 10133358 recursions server stats for thread 2: requestlist max 2673 avg 2234.27 exceeded 4287371 server stats for thread 2: 16992902 queries, 6698239 answers from cache, 10294663 recursions server stats for thread 2: requestlist max 2673 avg 2239.12 exceeded 4439600 server stats for thread 2: 17213660 queries, 6756507 answers from cache, 10457153 recursions server stats for thread 2: requestlist max 2673 avg 2243.8 exceeded 4594324 server stats for thread 2: 17432380 queries, 6812701 answers from cache, 10619679 recursions server stats for thread 2: requestlist max 2673 avg 2248.35 exceeded 4750633 server stats for thread 2: 17650889 queries, 6868541 answers from cache, 10782348 recursions server stats for thread 2: requestlist max 2673 avg 2252.86 exceeded 4907895 Thanks in advance for any suggestion you can give.