After upgrading zabbix server from 2.0.10 to 2.2.1 i have noticed that i have a huge snmpv2 queue in Administation->Queue.
Poller processes is about 40% busy.
I am started tcpdump and listening for snmpv2 packets. I saw a lot of GetNextRequest packets, which are sended to hosts, which contains items that was created with dynamic index (https://www.zabbix.com/documentation/2.2/manual/config/items/itemtypes/snmp/dynamicindex).
Next, i opened cpu graph on one of this hosts, and i saw high cpu utilization, caused by SNMPv2 packets. Looks like caching of this indexes works incorrect and zabbix server continuously trying to rebuild cache.