Server working very slowly

Maybe table types are MyISAM, not innodb ? If so, run this on your MOR database when you don't have any active calls:

 ALTER TABLE `actions` ENGINE = innodb;
 ALTER TABLE `activecalls` ENGINE = innodb;
 ALTER TABLE `acustratedetails` ENGINE = innodb;
 ALTER TABLE `adactions` ENGINE = innodb;
 ALTER TABLE `addresses` ENGINE = innodb;
 ALTER TABLE `adnumbers` ENGINE = innodb;
 ALTER TABLE `aratedetails` ENGINE = innodb;
 ALTER TABLE `c2c_calls` ENGINE = innodb;
 ALTER TABLE `c2c_campaigns` ENGINE = innodb;
 ALTER TABLE `c2c_comments` ENGINE = innodb;
 ALTER TABLE `c2c_commfields` ENGINE = innodb;
 ALTER TABLE `callerids` ENGINE = innodb;
 ALTER TABLE `callflows` ENGINE = innodb;
 ALTER TABLE `campaigns` ENGINE = innodb;
 ALTER TABLE `cardgroups` ENGINE = innodb;
 ALTER TABLE `cards` ENGINE = innodb;
 ALTER TABLE `cclineitems` ENGINE = innodb;
 ALTER TABLE `ccorders` ENGINE = innodb;
 ALTER TABLE `cdr` ENGINE = innodb;
 ALTER TABLE `codecs` ENGINE = innodb;
 ALTER TABLE `conflines` ENGINE = innodb;
 ALTER TABLE `currencies` ENGINE = innodb;
 ALTER TABLE `customrates` ENGINE = innodb;
 ALTER TABLE `days` ENGINE = innodb;
 ALTER TABLE `destinationgroups` ENGINE = innodb;
 ALTER TABLE `destinations` ENGINE = innodb;
 ALTER TABLE `devicecodecs` ENGINE = innodb;
 ALTER TABLE `devicegroups` ENGINE = innodb;
 ALTER TABLE `devices` ENGINE = innodb;
 ALTER TABLE `devicetypes` ENGINE = innodb;
 ALTER TABLE `dialplans` ENGINE = innodb;
 ALTER TABLE `didrates` ENGINE = innodb;
 ALTER TABLE `dids` ENGINE = innodb;
 ALTER TABLE `directions` ENGINE = innodb;
 ALTER TABLE `emails` ENGINE = innodb;
 ALTER TABLE `extlines` ENGINE = innodb;
 ALTER TABLE `groups` ENGINE = innodb;
 ALTER TABLE `hangupcausecodes` ENGINE = innodb;
 ALTER TABLE `invoicedetails` ENGINE = innodb;
 ALTER TABLE `invoices` ENGINE = innodb;
 ALTER TABLE `iplocations` ENGINE = innodb;
 ALTER TABLE `lcrproviders` ENGINE = innodb;
 ALTER TABLE `lcrs` ENGINE = innodb;
 ALTER TABLE `locationrules` ENGINE = innodb;
 ALTER TABLE `locations` ENGINE = innodb;
 ALTER TABLE `payments` ENGINE = innodb;
 ALTER TABLE `pbxfunctions` ENGINE = innodb;
 ALTER TABLE `pdffaxemails` ENGINE = innodb;
 ALTER TABLE `pdffaxes` ENGINE = innodb;
 ALTER TABLE `phonebooks` ENGINE = innodb;
 ALTER TABLE `providercodecs` ENGINE = innodb;
 ALTER TABLE `providerrules` ENGINE = innodb;
 ALTER TABLE `providers` ENGINE = innodb;
 ALTER TABLE `providertypes` ENGINE = innodb;
 ALTER TABLE `quickforwarddids` ENGINE = innodb;
 ALTER TABLE `ratedetails` ENGINE = innodb;
 ALTER TABLE `rates` ENGINE = innodb;
 ALTER TABLE `recordings` ENGINE = innodb;
 ALTER TABLE `rights` ENGINE = innodb;
 ALTER TABLE `role_rights` ENGINE = innodb;
 ALTER TABLE `roles` ENGINE = innodb;
 ALTER TABLE `serverproviders` ENGINE = innodb;
 ALTER TABLE `servers` ENGINE = innodb;
 ALTER TABLE `services` ENGINE = innodb;
 ALTER TABLE `sessions` ENGINE = innodb;
 ALTER TABLE `subscriptions` ENGINE = innodb;
 ALTER TABLE `tariffs` ENGINE = innodb;
 ALTER TABLE `translations` ENGINE = innodb;
 ALTER TABLE `usergroups` ENGINE = innodb;
 ALTER TABLE `users` ENGINE = innodb;
 ALTER TABLE `voicemail_boxes` ENGINE = innodb;
 ALTER TABLE `vouchers` ENGINE = innodb;

 ALTER TABLE `calls` ENGINE = innodb; 

To complete this query your server will need some time, from several minutes to several hours, depends on database size and hardware.