Red Giant spot clone tracker. Ho to improve time of calculating

My suggestion; simplify.

I am assuming that you have one shot that is 1800 frames long or about a minute and 15 seconds long that absolutely must be used in the final movie without any cuts. If that is the case, then continue working on all 1800 frames. If that is not the case, and I don't remember a single film that I have worked on in the last 25 years that had one shot that was over a minute long, cut the shot up into the segments that you will be actually using in the final edit and work on them one at a time. You'll have more comps but if you are going to edit this shot it will save you a lot of time later. VFX should be one of the last steps in the editing process, not the first.

The second part of simplifying is to run one spot clone track at a time. Trying to run 15 of those at the same time would slow down any machine. You might even consider putting the footage layer in a separate comp with no other layers, running spot Clone on that layer, then adding another instance or two of Spot Clone, then using the Composition/Pre-render menu to render and replace that comp in the project before you start using the other trackers. I have edited my output module templates (Edit/Templates/Output Module) to use my favorite frame-based 10-bit visually lossless with straight alpha format because I use Pre-render all the time.

One other option would be to split up the footage layer into 10 or 20-second pieces using Shift + Ctrl/Cmnd + D and run Spot clone on each of the new layers. I split up Rotobrush layers all the time because Rotobrush tends to slow down on longer shots, I can freeze the shorter segments or Pre-render them as needed to protect the project and reduce AEP file size by deleting the resource-hungry tools like Rotobrush and Warp Stabilize.

Let us know how that works. I can't think of any situation where I would try and run 15 trackers at the same time.