Does it really matter though since how many situations involve 100 timers being loaded at the same time?
Yes it does matter. It could also be 100 scripts each using one timer. And it will be noticeable with far less than that.
I think a 1-2 sec lag is pretty easy to live with.
You're kidding, right? We're not talking about network lag, but about mIRC being unresponsive for 1-2 sec, with a 100% CPU spike. If you find that acceptable, then you don't have a very fast PC to begin with..