I'll take a stab. My apologies if I'm telling you stuff you already know/have tried.
Please try these, one at a time, and restart your game each time.
1. Make sure you are using the current version - 17.0 (B240) stable as of this writing. If you opted in for the experimental versions, then you probably already know how to check this.
2. Verify local files: Open your Steam library, right-click on 7 days to die > Properties, click the Local Files tab, select Verify Integrity of Game Files. It'll take a while, depending on your setup. Any corrupted or missing files will be re-acquired and installed. If you have any mods or edited xml files installed, they will be overwritten.
3. Verify you have enough free space on whichever drive the game is installed on. I recommend a _minimum_ of 50Gb of free space so that games can write/update files as needed. Fortunately(?), 7D2D keeps most of its updates in your user profile.
4. Verify you have enough free space on whichever drive your user profile is on. 7D2D normally stores its player/map info under (Win10) C:\Users\<UserID>\AppData\Roaming\7DaysToDie\Saves. I recommend a _minimum_ of 100Gb of free space on whichever drive your OS and user profile are sitting on (troubleshooting with too many family members who like to sync My Photos with whatever cloud storage service they use). If you've got a lot of directories under there, consider deleting the old ones and their contents.
5. Try re-running the game with NO OTHER APPS RUNNING. I'm noticing that the latest version of Firefox browser is doing Very Bad Things with memory management and disk access on my box. I normally have Firefox running in the background so I can watch youtube while waiting for night/crafting timer to pass. I've had to be careful this past week, or use Chrome. (This does NOT mean that 7D2D couldn't use a generous optimization overhaul - which various mods and devs have said is on the schedule.)
6. If none of the above applies or fixes it, then it gets harder. Check your OS logs, for example (Win 10) Start > Control Panel > Administrative Tools > Event Viewer (there are lots of other ways to get to this, including click the the little window icon in the lower left and typing "Event Viewer"). Expand Windows Logs > Application, and Windows Logs > System. These may give some clues as to where you can try troubleshooting next. You can also try pulling up Task Manager while 7D2D is running and seeing if there's a RAM or CPU bottleneck (you never know when that AntiVirus software decides to freak out and eat your disk I/O).
Please post your results in this thread, as it may help others with similar problems. I hope my recommendations are useful in getting you back to headshotting Z's soon!
