Your best bet is to pickup a new flash drive. Luckily, a quality 256 gb flash drive is like $25 now.

7zip also allows for higher compression levels than the built in Windows tool. Would check that out as well.

One Time Pads are nice, as they are the only mathematically proven way to encrypt something in a way that it cannot be decrypted without owning the key.

a 3rd partition formatted to FAT32

exFAT is also pretty solid for this purpose and doesn’t have the file size limitations that FAT32 has.

The biggest thing is you have changed a random write to a linear write, something HDDs are significantly better at. The torrent is downloading little pieces from all over the place, requiring the HDD to move it’s head all over the place to write them. But when simply copying off the ssd, it keeps the head in roughly one place and just writes lineally, utilizing it’s maximum write speed.

I would say try it out, see if it helps.

Also, if the HDD is having to do other tasks at the same time, that will slow it down as the head can only ever be in one place.

But it’s getting so hard nowadays

It’s a sliding scale; it isn’t just ‘full privacy’ or ‘no privacy’. Everyone makes compromises somewhere based on their personal preferences. Most people would agree posting their credit card number on a public forum is too far into the ‘no privacy’ band, for example.

how does privacy improve the world

It’s up to you, but I don’t like trusting my personal info with untrustworthy companies.

Best description of this I have seen is: the 5th Amendment protects compelled production what you know. It does not protect what you are (fingerprints, hair, etc).