Agreed, this should really be a separate checkbox.

In upstream/vanilla Slic3r, it's a checkbox in Print Settings -> Infill. It would be beneficial to have that here, too.

I agree what was said here, and also think more control should be made to the user.

This gap fill is superfluous (to me), resulting in miniscule extrusions to patch a "gap" that doesn't really exist for every single layer, for every single perfectly tangential connection. But on the other hand:

This is a real gap, and something I'd like taken care of.

As it is now, I must either choose to waste a considerable amount of time, or have some critical areas poorly printed. This combination of factors is due to a chamfer at the base of concentric holes. It is incredibly common for any part designed for 3d printing, and the slicer's inelegant handling of this is likely wasting a lot of time.

Napkin math:
5 holes,
10 "gaps",
10 travels,
Each travel ~0.5s.
21 mm part,
0.3 mm layer,
Which means on this print I'm losing 6 minutes(!) of machine-time due to this issue

I'm confused by this being both a "Speed" setting, rather than a toggle and even as a speed setting not taking some kind of percentage. Everything else is dynamic/relative - it adjusts for bridges, curves, etc. but the gap fill is an absolute value.

How do I figure out what that value should be, given that it's going to be used in a totally arbitrary number of places in any given model?

Came hear to say the same thing.
In addition, setting the gap fill speed to 0 does not remove travel to the areas where gap fill is deemed necessary so the travel moves remain but there is no extrusion in that area. We need to be able to completely disable the gap fill feature.

There should also be a setting to indicate what to fill, for instance "Fill gaps that are at least 70% the nozzle width", this should allow us to filter minute gaps that doesn't make sense to fill and would result in moves that actually affect print quality (like printing 3 walls with 0.5mm nozzle and the slicer tries to fill some minute gap in between them".

Or allow to activate an option to fill only "areas of X mm²" or make it as "mm of filament".
In Cura this is called "Minimum Infill Area" in mm².

Something like that would be great.

Same here, please make at least the checkbox to disable the feature, but the above comment "Minimum Infill Area" sounds pretty good.

Hi guys! I opened a PR adding separate checkbox for gap filling here: #5999

Disabling gap fill explicitly will be possible in PrusaSlicer 2.4.0-alpha1. Thanks @xorza for the PR.
Closing the issue.