Are there some good references or is there someone who knows the scale of the difference in computation between REML and HE to estimate the variance components in a mixed effects model, say in GCTA fastGWA?

I have seen some papers showing HE having wider CIs so I am quite hesitant to use it, but I have a longitudinal model which I know takes a lot longer to run than a cross-sectional GWAS. I am trying to balance speed vs point estimate accuracy but currently have no idea of how big the difference is in terms of run time between these 2 estimators.

Thanks in advance!!

(Note: I am considering to do a GWAS on the delta of pheno at t1, t2 and t3 as a last resort.)