Ok, could the problem have something to do with the HEAP size? Another range error I got now is Failed to execute 'getImageData' on canvas rendering Context2D out of memory ImageDataCreation... perhaps not I don't know. I'm not as savvy with computers like I used to be lol Apologies for all the problems I know this is your baby that you worked on for so long. My experience with RPGMaker isn't what it used to be since I haven't used it in many years especially since it was the first RPGMaker again lol. I will ask around for you for solutions though.
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!