Different font size in dynamic font causes heavy load in memory?

It seems different font size in dynamic font would create the its own texture of all characters on the fly. Say i am using 50 font sizes it creates 50 of used a-Z in font texture, but it does clear the ones not shown after pause and resume the game.

Here's the Font Texture in Editor just after running the game: Here's after pausing and resuming the game, it became containing only the leters shown in menu:

My question is, would this cause a heavy load in memory on start?

If this does, would this helps if I only use ONE font size throughout the game then use transform scale for sizing?

P.S. I am using NGUI, but I guess it's the same in UGUI too?