I may have posted on this before, but I couldn't find a similar post when I searched.
One thing that can slow down a GURPS game is calculating modifiers.
One simpler way to set a penalty is to just choose a total level of difficulty from the Task Difficulty list (Basic, p. 345-6)
The TD has 21 possible levels: +10 through -10.
Let's simplify that to 5.
Net conditions are:
Nearly Perfect: +8
Really Bad: -8
If using these levels, do not use any other modifiers except those that are specifically inherent to a character. If your character gets a specific bonus from a paid-for advantage or a specific penalty from a disadvantage or quirk (or vice-versa), include that. Otherwise . . . this is it. You can't fish for any other benefits.
This wouldn't fly well with a group used to dealing with specific penalties and bonuses, and who have designed characters around those specific bonuses. But for a group used to playing a bit fast-and-loose with modifiers, this might make the process of figuring out what to roll against much easier.