Make sure when you are re-installing you have removed any trace of FeralHearts main folders.
I think your best option is to switch from Open to Direct. Now you said its your only option in being in Open, but try opening up your Feral Heart game, and then go to Options>Video. There you will be able to switch from Open to Direct.
Another reason probably is cause with the amount of people wanting to play Feral Heart, it does make everything more laggy. Especially when the maps are now able to only hold up to 300. Simple as it is, the more people that are on the server on a specific map, the more lagg and crashes you might have.
If all fails then try to re-install the game or try to make more RAM memory on your computer. The more space you have in your computer, the more smoother it runes
NOTE: Feral Heart + is no longer active anymore. The creator of that took it down for everyone and you are not able to play on that anymore. Simba is -remaking the Feral Heart + and it wont be for regular download as it used to be due to the face that the real FH dosn't support fan made versions of it. When FH+ is done and ready, it will be placed where regular maps are