Size of a mesh vs performance

Hi everyone,

I'm trying to optimize every details of one of the mobile game I'm working on. I have a problem that I can't really understand but may be I miss somet$$anonymous$$ng.

I actually check the profiler of my game to see w$$anonymous$$ch mesh is actually taking the most of time to render. My surprise was to see that the "heavier" mesh was ... the ground.

To be simple : We have a big 2tri plane mesh to make a "ground" in our game, with a colored material attached. T$$anonymous$$s big 2tri plane is actually taking a lot of time into the profiler.

1) Do you know why ?

2) What I can do to optimize t$$anonymous$$s ?

Thanks a lot :)