I have been active in the modding scene since around 2004 and have created mods, maps and especially custom models for games such as RtCW, Call of Duty MW, BF2, Counter-Strike Series, ETS2, Cities Skylines, Transport Fever and many more and had a lot of fun doing it.
But I never had to convert models via an extra website. This is by far the stupidest thing I've had to do so far.

Example:
I created a simple door model in Blender (Lod_0 22 Verts).
The upload sometimes (approx. 500 kb file size at a 1mbs upload rate) takes almost 1 or two minutes. Why is this taking so long?
The conversion takes even longer (up to 10-15 minutes) , for one model only.
If the model ingame don't looks as expected I've to retry the whole process.

Why is it so awkward and why don't you let us convert our models on your own computer?

I was thinking of creating a collection with different models, but that would take forever, just because of the conversion via the site.

Please give us the opportunity to convert models locally !!!