Tixati = v3.19 (portable)
OS = Windows 7, 10

There seems to be an issue where RAM consumption increases after enabling Channels, but doesn't return to its previous level after subsequently disabling Channels.

So for example, after enabling Channels for a while, then disabling it, channels2.dat and channels2.dat.lastloadok.dat had each become 110 MB. And then running Tixati without any active torrents, RAM consumption was:
* Working Set = 274 MB
* Commit Size = 250 MB

But after stopping Tixati, renaming the Channels files above to *.bak, and re-starting Tixati, RAM dropped to over 1/5th of its previous size, and Swap dropped to over 1/8th:
* Working Set = 54 MB
* Commit Size = 31 MB

Nothing? Seems like an actual legit bug. Although not terribly serious/high-impact.
Anyway, the work-around in my OP seems to work fine for now.
Let me know if you're unable to reproduce, and I'll try to retrace my steps.

I had commented before that disabling channels doesn't reduce memory consumption until a restart. I didn't try to rename files entirely. I think this is a problem too, because channel data has no deduplication and takes up a lot of memory.