I'm not sure whether all of these steps work in maniaplanet, but hopefully some can cut down the file size:
o Remove or adjust embedded objects
Embedded objects take up space in the map file. Also, removing icons from the objects can reduce the size of the objects themselves.
o Ghosts in the MT
Replays imported to the MediaTracker usually bring the file size up a bit. If you still need to have ghosts in your map, consider making a different version of the map with as few blocks and as little MT as possible, and record the replay there.
o Tamper with the shadow calculations
Not sure how effective this is, as I haven't tried it at all. As you probably know, shadows take up quite a lot of space, and it will always do. Even if the embedded lightmap image is always the same size (1024x1024?), the compression could differ between the different quality presets (Fast, Normal, High, Ultra).
o Modify the track screenshot
As the last resort (if you're just at the limit), you could set the camera position to areas with little detail as possible (such as the sky or total darkness). I believe the screenshot itself is stored in some way in the file, and the compression could make a small difference.
The most used workaround, however, is just to make an alternative version of the map with less scenery, less MT and fewer details for online use. I ended up doing that many times as well
Last edited by Voyager006,