Memory issues have been reported previously but I've gathered that new such issues continuing with 0.99.128-rc should be reported again.
The issue I am seeing is growing memory usage over time with overall slowdown. WIth 24 tabs over 13 windows (including this one), new windows can take 1+ seconds to open and sometimes typing gets slow (not terrible but not "snappy").
This instance of Orion has been open about 4 days and the main process is showing almost 5GB in Activity Monitor.


After quiting the above session, Memory Used was 6.4 GB (down 6 GB from above), App Memory was 2.7 GB (down from 6.7 GB), Compressed was 1.1 GB (down from 2.5 GB), and Wired was 2.5 (down from 3.1 GB).
I've also saved a Sample of the main process if helpful.
Note this is not repeatable in that I can give a concise list of steps to repeat but it is repeatedable in that memory usage eventually gets this way after several days (usually more than 2 and in this case 4). Also if I don't quit and restart after enough time, Orion crashes (I'm guessing it runs out of memory).
Ideally Orion's memory usage woud be a function of the windows/sessions open and not change over the same time. That is memory usage over time shouldn't go higher than Orion after quitting and restarting with All Windows From Last Session.
Here is Orion after resuming the session from All Windows From Last Session:

Here is Orion after making sure to touch after tab on every window:

The biggest difference then seems to be that the Orion RC main process and Networking process are much bigger and this leads to more Compressed memory. But then as I am guessing the data in Compress memory is part of Orion's working set so the system has to keep compressing and uncompressing Orion's data which causes it to feel slow.
Version 0.99.128-rc
Catalina (10.15)