Whole time, background animation increasses lag after many hours playing. You can check RAM it takes by pressing Alt+Ctrl+Supr then if the game is eating a lot memory you can kill this process to get RAM back at normality then open newly the game.

I suggested some options to reduce lag but I got no listened, speacially an option to disable background animation the rest I don't care much. I noticed when the screen is still black (when game is charging)it plays really fast and soft.

Yes, it happens with any crusaders at any time. Just before typing this, I refreshed after starting a new objective, so I was on area 1 with only a few crusaders in my formation with minimal skills bought. The momentary stops are very, very slight at the moment due to just refreshing in a new objective, but still visible. After buying Mindy's "Mimic" skill and letting it self-refresh several times, there seems to be no difference, for better or worse. There has been no clicking, and the only buff currently active is a mission-obtained DPS buff. I will let the game run for about an hour and edit this to note if the issue has gotten more noticeable.

Update: An hour later and it seems to actually be slightly smoother. Huh...