Well i really don’t know what’s up. I left it over night processing a delete, and when i came back to continue this morning they started going faster, a lot faster. i got excited and then after maybe 6-7 events deleted they started chugging again. I’m not sure if this matters but i had a second library from the same drive open at the same time (although i did try this process with only one library open and it was the same). One event i came across I moved to that second library via right click and it went super slow too. So maybe not just a delete issue. After several hours I ended up finishing the task of culling the events from that library and eventually deleted it entirely once the events were moved out to other libraries or deleted themselves.
Out of curiosity i ran disk first aid, all green lights. I ran AJA disk speed… the USB disk reported 250mb/s …. my mbp ssd reported 2600mb/s. Does the fact that its exfat formatted make a difference?
ps. the second library a have on that USB disk is 3.5TB with 3000 clips…. and it responds quite quick. Possibly the first fcp library with the slow deletes was buggered under the hood.