Can I Run it? Multiple pages, effects etc. low bandwidth?

Hi all. My next game will have: me and 4 players 2 maps (page size 27x29) with dynamic lighting and 10-15 light sources each. 14 scenes (page size 12x9) half of them with dynamic lighting and/or FoG effects and roll20 store bought weather effect layers. Syrinscape online player Discord for voice 10-12 mbps download 2-4 mbps upload Windows 10 + Google Chrome We i be able to run my game steady and stable? Thanks Rune

Sounds stable, though if any of the weather overlays (or any resources actually) are animated, you may have performance issues with them.

How about gif pictures in the background layer? In 10 of the scene pages (size 12*9) i have a 2 second gif picture looping (size 4-6 mb) example: a gif picture of a living room with a live fireplace and falling snow outside windows. Are these lighter than the weather effect layers in regard to bandwidth?

Someone else will have to answer that one. I generally don't use animations of any kind, partly because of potential performance issues, and partly due to personal preference.

gifs will loop for X times then eventually slow and die.  Roll20's limited by the hardware of each user, I personally don't even bother with weather and animated gifs except when posting memes.  Also on a prep/DM advice side of things, it looks like you are putting alot of prep into showmanship, that is a great style choice but ultimately most players can get by with a good theater of the mind experience, and that means you could probably drop alot of that flashy prep and focus your prep time on content instead.  Something I learned over time.  most of my players can't even stand dynamic lighting at all in my sessions they only prefer it setup on dungeon crawls.  Most dnd players want to play dnd not a video game.