I haven't noticed a difference but this company is significantly more trust worthy IMO

You don't use Mullvad for their performance, you use them for their insanely paranoid security and privacy practices.

And for the record, I was never impressed with Surfshark speeds. I dropped them when they bundled a virus scanner into their VPN client, that's sketchy as hell. I don't want my VPN provider scanning my files.

I never had any real issues with speed using Surfshark, the reason I made the switch was largely about trust. As another user said, as soon as I saw Surfshark start their YouTube advertising spree, and start to bloat their client with unnecessary features, I started looking for alternatives.

I'm iffy about any VPN company that uses YouTuber marketing as it is, and while my threat model isn't overly paranoid, I believe the VPN company someone chooses to use should have paranoid business practices. After I saw the news on Mullvad's raid, the authorities subsequently finding nothing, and the fact that a user's account is merely a string of numbers, I decided it was the VPN for me.

Mullvad compared to PIA, Google annoys me less with recaptures. I know it doesn't answer your question but thought I'd throw my 2 cents in since PIA was quite a popular choice with their YouTube sponsor slots and cheap prices