Hmm... The web version should not be too taxing on the PC. Are you using Chrome?
Also, may I ask your computer specs? Processor, memory and GPU?
Viewing post in Delivering Hope (hololive fangame) comments
I see. Probably the computer specs are a bit low for the game.
You should seriously consider getting a newer PC. That's a 15 year old processor you're using there. Pretty cool that it still works to this day, but it may be a bit slow for comfortable gaming. A dedicated GPU will help a lot too. If you don't plan to game often, just get the low spec ones and it should be fine.