THIS REALLY WORK IT DOES NOT HAVE TO DECOMPRESS EVERYTIME YOU RUN IT AND IT DOES NOT LOWER IN-GAME QUALITY!!! DON'T LISTEN TO WHOEVER SAYS IT DOES!! TRY IT FOR YOURSELF AND YOU WILL SEE IT WORKS!!!
This should also help with lag but is mainly so maps load faster, I do this all the time and it loads about twice as fast. Well here it is.
Go to your nexon folder that has combat arms inside usually: C:\Nexon
in the Nexon folder find the Combat Arms folder.
Once you find the Combat Arms folder, right-click it and select properties.
Go to the General tab if not already there. Click the Advanced Button.
Then Checkmark the box that says "Compress contents to save disk space".
Press OK then apply to all folders and files in the folder.
If you have done it correctly then the Combat Arms folder as well as everything in it should now have blue lettering.
Your maps should now load faster.
If I helped you then the least you could do is thank me by clicking the thanks button.

And to Moderator that sees this could you please Sticky this!
