So I updated to 2.0.7 and minecraft uses like 1gb more ram and multiple enderio chickens have their texture broken.

EnderIO chickens fixed. Will look into the ram usage.

Yep those are good now but ram usage starting mc is way higher. Multiple times hitting red on 4gb on 2.x and never on 1.3

i have some issue starting minecraft with new update take 15 minute to start without update 6 minute
this is a very problem for me

Changed to only reload resources a second time if absolutely required. Also changed it not to create models until they are actually used in game, which should improve load time and RAM usage even more.

so from what I understand, only the first time the pack takes so long to load ??, it doesn't seem to me ..... but I don't know if I understand what you mean

Because of version 2.0.9, the resourcepack is loaded twice ("Reloading textures"). On the 3rd stage of loading Forge and on the 6th. Version 1.3.0 works fine.
Load time 155 mods (+ Roost 2.0.9)=284 sec. - https://gist.github.com/kellixon/fdb62053adfe8c109c463bb0a1ae71a6
Load time 155 mods (+ Roost 1.3.0)=211 sec. - https://gist.github.com/kellixon/7fc5e25c11df9f7e90bcb07cadb9db0f

Should be fixed in 2.0.10