So the KF1 SDK is slow, annoying and terrible, in this guide ill show you how to make it a little faster, less annoying and alright.

This will be some basic easy fixes but will help you drastically.

The 2 most basic things are...
1:
Disable Steam Overlay for KFEd.
Simply open properties of KF SDK, and find use steam overlay and turn that off.
2:
-nogamma
This launch command will fix the screens gamma brightening when opening KFEd. This will work for any UE2 editors that do this. You can set this in steam launch options or your shortcut if you use one.

These are some replacements that will make your editor experience better...
1: Selection Fix
This will fix the stupid annoying freezing when you are selecting actors. Before I show this here is some side notes:
Backup original file!
This fix causes some small side effects like not being able to select through coronas, some modulated surfaces (you can use wireframe view to select.) Some shader editors also become crash prone so keep the old one on hand. Also if you use the older d3d video driver in game you may have some issues with this.

Anyways now to the download. This patch is by Metallicafan212 and he also did some other UE2 games such as Red Orchestra and Unreal Tournament 2004.
Get it on GitHub[github.com]
Simply put this file where the regular one is in KillingFloor/System.

2: LAA KFEd.exe
You can do this yourself but enabling Large Adress aware on KFEd will help with crashing, it lets KFEd use 2 more gb of ram. Before this are some side notes:
Windows Defender might act up.
This file is safe, everyone who maps in ST has this file in their game. but windows defender hates exe files. If it acts up just add an exception to the new KFEd.exe.

If you are lazy and don't wanna learn how to do this like me you can get this from the Siren Torturers Community Server downloads page[sirentorturers.site.nfoservers.com].
Look for KFed-4gb.zip this archive has the LAA enabled exe file.
To install just replace the exe in KillingFloor/System