SEPM console hanging often after upgrding to 12.1.5

We've been using SEP for quite some time steadily upgrading to every next release. SEPM server is the same VM with Windows Server 2008 for many years. 12.1.4 was ok. But after 12.1.5 it often hangs when i try to login to console. Even the login window is slow to appear and then it just stays on loading. If it loads sometimes, it then doesn't show any info in the console. Usually i have to wait for an hour or so and then it is back to normal. I don't see any unusual CPU/Memory usage during such hangups. I have moved log truncating and database indexes rebuilding tasks out of working hours. I can give more RAM to it, but i'm not sure this is a solution.