This is critical for the trends-evaluation, which does collocation in monthly data which takes 45min for 4 periods without model-maps. Model-maps for one period takes 6h alone, since daily data is read.

I've started on the problem in #1312. If I understand the problem correctly, this should solve it, even though it is not in the most elegant way:

I'm testing out simply changing main_freq to maps_freq when the maps are calculated(or the coarsest freq if that option is chosen). It of course then colocates the obs wrong. It seems that ModelMapsEngine creates a colocator, but only uses the model data, in which case the obs are irrelevant. And as I understand it, the obs shown on the map are created elsewhere, so this does not matter anyway(?). The obs shown will also be just the July data for that year, and not a mean of the year.

The freq change is done for all models, no special case for EMEP. I can change that to check if the model is EMEP, as we are not always sure to have yearly data

I think my code is a bit misplaced, but due to the overuse of OOP, it is not easy to know where things are happening. But we can discuss that later