outlook to exchange slow

[Remedy]

after the free to paid migration im getting different clients / businesses reporting their outlook is very slow talking to on prem exchange. sending an email has a spinning icon for 30 seconds, incoming can be anything up to 3 minutes and this all started in the last week.

at the moment i have globally turned off mail,antispan and the firewall until i get an answer, but im not sure if these have made any improvement.

no avast on the exchange server, endpoints only.

thanks
terry

[REDACTED]

I've noticed the same behavior to our POP clients (Thunderbird, Outlook 2007, 2010 and 2013); product is Avast Business Cloudcare. This started happening in around the same timeframe (1-2 weeks ago)

Disabling all security on Avast doesn't seem to impact performance, but everything operates normally if Avast is uninstalled.

[Aleksandar34]

This same situation I'm experiencing. After migrating from free to "Business" version all clients from Outlook 2010 to the latest Office 365 having incredible slow downs in opening Outlook, sending mails and very often "Outlook not response" or "Avast plugin coses Outlook to slow down" pop up messages. This started happening 2-3 weeks ago. The situation is very frustrating because only solution which gives result is to disable Mail Shild.