not sure if that's what you mean, but try setting a higher priority

Invoke task manager, go to Processes tab, right click thebat.exe -> Set priority -> choose 'AboveNormal' or 'High'.
Do NOT choose 'RealTime'.

To start a program with priority <> Normal create a .bat file like this
CMD /C START/desiredPriority fullPathToExecutable

fullPathToExecutable should be in "" quotes if there are spaces in it.

BTW the problem is unlikely to be in theBat.
Configure your AV not to monitor theBat folders (installation, mail, if there is a theBat temp folder).
Other security software, like Comodo Defense+ or Sandbox features, may also cause this.
Check what starts automatically and remove useless stuff - google for Autoruns or startup control panel(simpler to use)
See if drives need defragmentation, if system drive and drive where %temp% is(if different) have enough free space.