I dont think you can lower fps on osbot standard injection; I do run my bots in norender mode (the slaves atleast), and as for lowresource/lowcpu , I am avoiding this because my bot requires scanning players on log in.
My main point is, before the osbot update for this new osrs update; I was able to run 20+ slaves + 1 mule only using 90% CPU overall, each client was only using 0-3% and my mule being logged off was always 0-1%... not sure how it jumped from that to 10% , 10-15% for each slaves, thats a ridiculous amount of jump imo for a small runescape update..