I think I abused a little too much of the parallel process. If doing certain actions, then there will be around 30 to 35 parallel events running at the same time. At first I don't think this will be a problem because the game seemed to run just fine and without lagging, but looks like I was wrong. Also, maybe some scripts were not as compatible with each others as I believe they were, so there could be the problem too.
Anyway. I'm thinking of redoing it from start, or maybe use this game as an sketch to try and do something better... If my real life works allows me, that's it lol.
Thanks for your help. If you find some kind of solution, please let me know. If its something I can do in my spare time, I will try to fix it as soon as I can!