Why are you telling me to exclude the program from my Antivirus software?
Antivirus software is a must-have in today's age of computing if your PC is attached to the internet at all. (Some will argue otherwise, but for 95% of PC users this is a simple fact.)
Unfortunately, the scans that it runs on active processes can have an negative impact in your game clients performance. Since we trust Steam, and their vetting process, to prevent us from being sent malware through games we purchase, we can safely trust them as a publisher. As such, I recommend excluding the entire Steam folder rather than just your 7DaysToDie folder under SeamApps\Common.
In fact, I keep all of my games from trusted publishers in a "Games" folder, and have excluded that entire folder. Steam, Origin, and other such tools all reside inside of this folder, along with individually purchased games from other companies I trust.
You will also need to exclude your save folder in %appdata% It will be in C:\Users\<userName>\AppData\Roaming\7DaysToDie Mine for example is C:\Users\sylen\AppData\Roaming\7DaysToDie
How to exclude the program from your Antivirus software.
Truly, the biggest hurdle in doing this is figuring out how to perform the exclusion in your particular software. As such, I have compiled a list of the top 10 Antivirus solutions and am providing links to their instructions. Microsoft Security Essentials does not make the top 10 by any stretch, but I'll include it just because it is common if you haven't purchased a real AV solution.
1. BitDefenter (#1 for 4 years straight BTW)
2. Kaspersky (Used to be that Kaspersky and AVG were heavy contenders for #1 and #2, but Kaspersky has held #2 solid for a while.)
3. McAffee
4. Norton (Page 44)
5. F-Secure
6. Avira
7. Panda (It's from 2012, but it's the best they have available)
8. Trend Micro
9. BullGuard (You'll have to scroll down the page a bit for the instructions.)
10. eScan
11. Avast!
12. AVG (I think the biggest thing keeping AVG from ranking higher is the large number of false positives and the high impact on system performance)
13. G Data
14. Norman (It's convoluted, but the instructions are there)
15. ESET NOD32
16. Microsoft Security Essentials
If you don't have one of the above programs, just do what I did to get the above links. Go to the website for your antivirus software, go to the support section, search for "exclude folder", then follow the instructions to exclude the entire client directory. (Alternatively, you can also Google "nameofantivirus exclude folder".)