Hello Khaled.

I tried installing the latest version of mIRC in portable mode, I then added a simple line in remote.ini that would connect and join a bunch of channels on different servers.

The results were the same, the interface is freezing now and then. What I did and the results:
1) All servers + channels: Freezing.
2) Removed all SSL servers: Freezing.
3) Removed my quakenet server thus closing 20 channel windows: Freezing.

Right now I am currently connected to 11 servers and I still get freezes and I just monitored CPU usage and it jumped up to 37.8%.

I've worked my way down to 8 servers (20 channels in total) and none of the channels are particularly big, one of the servers I closed down had (3) channels, one with over 1000 users (if that makes any difference). The lag is starting to decrease but it's still freezing, just not as frequently.

It's pretty obvious that if I keep closing connections it'll get better. Not sure if this was valuable information or not but at least I tried.