AdmiralAlkex

@OP

Hi and Welcome to the forum!

I don't know what would be easiest, getting one language to run in the others SciTE, or run both, but why can you not run both simultaneously?
You might need to set check.if.already.open=0 in the user settings file, did you try that? (In SciTE, Options > Open User Options File).

@Michiel

There is a 64 bit SciTE?

You are either declaring them wrong or calling ChkUpdate() before line 75.
 

If you want something more specific, you'll have to ask a more specific question (READ: post code!).
 
Welcome to the forum

You are certainly not helping yourself by artificially throttling GUIGetMsg() down to just 20 runs per second. Look at it in the helpfile, notice there are a lot more things it returns than just clicking controls. Even moving the mouse generates a message.
 
If events are skipped, then you are filling up the queue with messages faster than you are removing them. Though it's more likely that they are just delayed (waiting to get in front of the queue) rather than skipped.
 
Simply removing that much too large Sleep() will help a lot. If you want your GUI even more attentive, then add
 

If $nMsg <> 0 Then ContinueLoop after the EndSwitch, so that way you deal with GUI things ASAP, and let the rest of the code in the main loop run when it's less disruptive. You can even keep that Sleep(50) then.

Edit: I missed that you were new. Hi and welcome to the forum!
Like hotkeys?
You could try these:
>GUIHotkey.au3
>GuiHotKey UDF
or search the forum for others

Here's one combination.
$Var = "Hello World!" Run(@AutoItExe & ' /AutoIt3ExecuteLine "MsgBox(0, ''' & $Var & ''', ''Hi!'')"')

Have you tried Process Monitor? It allows you to see writes, flushes and all that.