Wow after 8.1: clients freezes, crashing etc

After patch 8.1 I did not do anything with my hardware and softwares. No changes at all, just downloaded new patch and updated all addons I am using which are: ixboser, EMA and TSM, isboxer had no updated.
The problem is that after patch 8.1 game clients constantly freezes for miliseconds or even crashes on my 2nd pc. I tracking memory / cpu / gpu usage and the funny thing is that it even decreased after 8.1 then before. Yet game performance is very very bad.
On my 1st pc where i run 16 clients i have constantly micro freezes, where my fps goes the way as it was ~15 FPS on slaves and ~30FPS on main. Nothing has changed, there are the same as before, but still i have micro freezes while i`m tracking fps all the time and i did not recognize just before or during FPS drops... on 2nd pc i do not see any micro freezes, but game crashes, usually 1up to 3 clients - i`m running there 8 clients.
I have checked if there is a problem with addons and there is not. I disabled all of addons and tried to login and check at least my main while all slaves where still standing on background - the same, micro freezes every 2-3s.
So i am sure this is not addons problem.
Does anyone have simillar problem after 8.1? Were you able to solve it somehow?

Additional information
1. pc: i have cpu usage ~80% accross all of my threads (8 core cpu / 16 threads - these threads are used in balanced way); memory usage is around 26-27 GB / 32 GB. Before patch 8.1 i had above 80% cpu usage.
2. pc: i have cpu usage ~90% accross all of my cores (4 core cpu / each 2 clients uses separated cores, example clients 1,2 use core1, clinets 3,4 use core2, etc. memory is ~19GB / 24GB. before patch 8.1 i was almost all the time 98-100% cpu usage and was working perfect.

My next step is to reinstall game but i doubt it helps tbh.
If anyone had similar problem and solved it please share.

[bob]

Some people have had luck with using a round robin cpu strategy in ISBoxer.
Also, one guy had issues with the 417.22 NVidia driver. Rolling back to 417.01 resolved that. I note that 417.35 is now out though, so maybe that resolves something too if you are on .22

thanks for info. I am @ 417.35, no changes compared to 417.22. I do not know what drivers i had before but i was using the same one before and after patch. After patch not possible to play anymore and all drivers i installed did not helped at all.
I have changed some graphical options, run repair, nothing helped. Next step is reinstall game and if this does not help i will try to set round robin cpu strategy ...
GPU usage on 2nd pc is below 40%, while on 1st pc is 60-70%. If my cpu, gpu and memory is not loaded by 100% then where does these freezes / crashes come from ...

I have solve half of my problems.

After reinstalling game, updating patches, playing with different cpu strategies, updating / playing with drivers, finally i did 3 things which helped me.

1st pc where i had crashes of clinets, all i did is everything above which did not help. I have moved wow to SSD disc and also used CPU strategy that each slot/clinet uses all cores >>> I do not have crashes any more; game play is very smooth and there is only one thing which is annoying but still acceptable is long loading screen, like up to 5 mins.

2nd pc i did 2 things which removed microfreezes and game/pc crashes, do not know which one helped, but so far it works: i have dedicated each slots to use 1 core and 1 fake core >> slot 1: CPU 1,2, slot 2, CPU 1,2, slot 2: CPU 3,4 and so on. Additionally i have updated ISBoxer today morning, so these 2 options made my game working almost fine as before patch, which one helped? i do knot now, maybe only 1, maybe both maybe 2nd. But i`m glad it is working almost as before 8.1