Population-template extremely storage hungry

I am trying the population-template function, and it seems very storage hungry.
I am only trying it out, and it hasn’t completed yet, but the temporary folder has currently over 400Gb.
The input folder had only 24Gb with 4 FODs.
I will be running out of storage soon.
Any suggestions?

population-template converts input images to float32 and should clean up outdated warps and transformed input images after every stage. All intermediate templates are deleted at the very end. Temporary files and intermediate templates are not compressed for speed reasons. If you have many stages leading to many intermediate templates, that might be an issue. You could manually move or delete outdated templates such as linear_template* and nl_template* except the last one.

population_template options and a list of file sizes in the scratch directory (tree -sh population_template-tmp-XXXXX) would be helpful to diagnose what’s going on. Also, have a look at the templates, do they contain lots of empty space (zeros or NANs)? If so that might be an issue with the initial alignment and average grid computation.