Thank you for your reply and input! I will work on trying to improve the game, at least a bit.
I know the WebGL version underperforms and that bugs me. I hope I'll figure out how to make it run better while keeping it the same to the desktop version. I admit the Sentinel can get relentless in pursuing the player, but the idea was to, once being spotted, try to outrun it - with the speed difference you should be able to escape the cone. However, and that was deliberate, after attracting too much attention, the Sentinel was meant to never cease the pursuit, before that, after a while it loses interest in the player's ship. But I think you're right - I should look into rebalancing the mechanic, so an early screw-up should be easier to recover from.