First of all, reading comprehension for this bunch of commenters is crap.
Your WIFI is slow. 2.4 Ghz I assume? You could try changing to a different channel. 100 ft 2.4G with a router in the middle... gonna be slow. Assuming the router is in the middle and each getting 30ish, 10 is to be expected with packet collisions, etc. If not on antique WIFI even AC can be slow. Mesh is slower yet but they lie about it for marketing.
Here is a thought: Storage is so cheap you could throw a drive in one (an external USB drive) and then walk it over to the other for MUCH less money than a 100ft of cable.***
Here is another thought: Move the router next to one computer, move the other computer over and just do a short cable transfer via the ehernet.
100 ft of cat5 is ridiculous unless you are in a big building.
*** best solution.
It’s 2.4 and 5GhZ and picks the channel for me. I already have a box of Cat 5 left over from another job. The best solution so far is to check the auto negotiate on the cards. If I can force 100mbs that will be a good thing even if it has collisions. All I have to do is figure out how to do that.
Suprised that no one has even mentioned cable attenuation. But they’re right, use a portable drive. Why even bother hard-wiring unless this need to be a repetitive use. 100 feet. Are you going out of the building? If so you need to consider lightening suppression.