Investigate performance on long timeseries

[BSchilperoort]

Your work in reimplementing regridding methods is interesting! I often find ESMF to be a bit heavy on dependencies side indeed. But one crucial feature that makes it better than xr.interp is that it computes weights first and then applies them in parallel for all spatial slices. This is a major dealbreaker when dealing with long timeseries! Do you have plans on implementing something like that in pure-xarray ?

Originally posted by @aulemahal in pangeo-data/xESMF#282 (comment)

[BSchilperoort]

It should be easy to compute weights and apply them, the same way that the conservative method currently does. This way we could possibly improve performance for long timeseries.