Big delay in audio after answer queue call

[danial]

Hi
I 'm using Asterisk 13.20 and Freepbx 10.13 on a virtual server(8 cores CPU , 16 GB RAM ) we have multi queue and call recording
here is my problem: When queue increase in call volume (about 20 waiting calls ) calls ditributed normally but after agents answerd calls , there will be long delays in hearing the caller’s voice.

In log files there is a related warning message:
[2018-12-05 15:14:30] WARNING[31027][C-0000c3f0] channel.c: Exceptionally long voice queue length queuing to Local/1057@from-queue-0000fa42;1

more info :
-we have two servers with same hardware and software config and both of them have this issue .
-these servers connected to remote mysql (LAN server) by ODBC to store CDRs.
-All clients and servers are on LAN network without firewall or NAT devices , we don’t use DNS for client registering or trunks.
-Asterisk still working with no crash or core dump files.

in same time “queue show” command responses with delay:

2018 has 18 calls (max unlimited) in ‘rrmemory’ strategy (218s holdtime, 72s talktime), W:6, C:962, A:159, SL:85.4% within 60s
Members:
1162 (Local/1162@from-queue/n from sip/20050) (ringinuse disabled) (dynamic) (In use) has taken 11 calls (last was 110 secs ago)
1123 (Local/1123@from-queue/n from sip/20058) (ringinuse disabled) (dynamic) (Not in use) has taken 13 calls (last was 110 secs ago)
1113 (Local/1113@from-queue/n from sip/20044) (ringinuse disabled) (dynamic) (in call) (In use) has taken 4 calls (last was 32 secs ago)
1191 (Local/1191@from-queue/n from sip/20055) (ringinuse disabled) (dynamic) (in call) (In use) has taken 5 calls (last was 261 secs ago)
1057 (Local/1057@from-queue/n from sip/20054) (ringinuse disabled) (dynamic) (In use) has taken 8 calls (last was 494 secs ago)
1114 (Local/1114@from-queue/n from sip/20053) (ringinuse disabled) (dynamic) (in call) (In use) has taken no calls yet
1128 (Local/1128@from-queue/n from sip/20052) (ringinuse disabled) (dynamic) (in call) (In use) has taken 45 calls (last was 117 secs ago)
1189 (Local/1189@from-queue/n from sip/20059) (ringinuse disabled) (dynamic) (In use) has taken 16 calls (last was 274 secs ago)
1030 (Local/1030@from-queue/n from sip/20051) (ringinuse disabled) (dynamic) (In use) has taken 15 calls (last was 152 secs ago)
1364 (Local/1364@from-queue/n from sip/) (ringinuse disabled) (dynamic) (Invalid) has taken no calls yet
1115 (Local/1115@from-queue/n from sip/20062) (ringinuse disabled) (dynamic) (in call) (In use) has taken 17 calls (last was 70 secs ago)
Callers:

1. SIP/kam-dispatch-0001c313 (wait: 3:33, prio: 0)
2. SIP/kam-dispatch-0001c317 (wait: 3:22, prio: 0)
3. SIP/kam-dispatch-0001c318 (wait: 3:13, prio: 0)
4. SIP/kam-dispatch-0001c31f (wait: 2:59, prio: 0)
5. SIP/kam-dispatch-0001c324 (wait: 2:31, prio: 0)
6. SIP/kam-dispatch-0001c329 (wait: 2:11, prio: 0)
7. SIP/kam-dispatch-0001c331 (wait: 1:55, prio: 0)
8. SIP/kam-dispatch-0001c337 (wait: 1:42, prio: 0)
9. SIP/kam-dispatch-0001c33b (wait: 1:19, prio: 0)
10. SIP/kam-dispatch-0001c33c (wait: 1:11, prio: 0)
11. SIP/kam-dispatch-0001c33e (wait: 1:07, prio: 0)
12. SIP/kam-dispatch-0001c340 (wait: 1:01, prio: 0)
13. SIP/kam-dispatch-0001c347 (wait: 0:40, prio: 0)
14. SIP/kam-dispatch-0001c349 (wait: 0:34, prio: 0)
15. SIP/kam-dispatch-0001c34a (wait: 0:30, prio: 0)
16. SIP/kam-dispatch-0001c34b (wait: 0:23, prio: 0)
17. SIP/kam-dispatch-0001c34d (wait: 0:03, prio: 0)
18. SIP/kam-dispatch-0001c34f (wait: 0:01, prio: 0)

thanks in advance.