I have been testing some different ways to update ial, but i get lag in any way i have been testing, any good way out there to update ial without the lag? tested to delay it (last attempt) but no luck with that. so someone that have a good example on how to do it, or that can explain how to solve the problem?

/who # on join is the simplest way.

There will always be a slight lag when there are a lot of users because of the amount of data you need to receive.

The problem i got is how to use the who command, if i join 10 channels with 50+ on every channel = 500 users, then i will be laged as h*ll.. that is what i trying to solve, i was asking here like 4 years or so ago about this, but it still lag me if i join to many channels. And i cant solve that..

Your only option is to stagger /who. This, of course, means that you won't have updated IALs on every channel right when you join. From experience, a lot of users disable anything in their script that tries to update IAL on join because of the inherent problems. Rarely is there enough benefit gained in a script's feature to make it worth the hassle.

You could always join 1, /who # , wait for the raw numeric 315 and then join another and so on until you get them all done.

Thats how i do it now. And still this cose me to lag a litle to much to be ok..

Then do it on a timer? Ie. five seconds after the last who ends, you start the next one.

mIRC has a flood protection feature which can be used to queue up your own commands if your connection is under heavy use. I'm not quite sure how this works with queueing your outgoing packets when the heavy usage is coming from inbound data, but you could try this. If it works, you won't have to do anything in your script at all. Flood protection is in Alt+O -> Flood. Just make sure to toggle "Queue: [x] own commands", and you may have to play with the bytes value that triggers the check.