If your problem is the freeze from writing text, you can try using /fupdate
Each time your mirc begins, it forgets the /fupdate setting and reverts to 0
You can put a /fupdate 100 in the ON START event to make screen writes faster.
If it's too fast, can change to another number in the 1-100 range.
Without a number parameter, /fupdate tells you the current setting.
Thanks for your answer.
I did /fupdate and mirc returns 0 and i did /fupdate 100.
I believe the freezing is probably caused by reloading logs or mirc waits for more data from playback or loading some font. Like in: znc-playback, freeze for one-n seconds, more playback, bit of freezing, more playback.
What bothers me more it's that i have to wait until mirc to draw stuff and i can not always be there to minimize channel windows. I probably didn't say in first post but i have a znc that i usually go each 3-4 days basis and i noticed if i click minimize to the current channel during playback, playback is faster because mirc "doesn't have" to waste cpu to draw stuff but does draw everything and takes just few seconds instead of 30s+ seconds.
And i also dont want to have to have channel windows in restore and maximize after playback by myself.