Hello Mick
As a relative newcomer myself, to the world of map making, I'm not sure if it's possible to "downsize" the two files you mentioned.
The map is 1:1 ratio and with Sri Lanka being such a big island, I just managed to squeeze everything in at pretty much the limit of possible map size (in fact the Gimp editor spat out the first few attempts as too big). The map takes a while to load, but does, I feel, provide a realistic and expansive "world" during missions.
I think the only way to make the files smaller would be to create an entirely new map at say 1:2 or 2:3 ratio, but this would of course also alter the height and size ratios of hills, mountains and other geographical features, changing the perspective and giving a less realistic landscape.
Also, to depict the Indian Ocean WW2 naval battles it was important to have the island in context compared with the surrounding ocean and mainland India, hence a significant amount extra data with including SE India.
Not sure how far the number of objects affects file size and gameplay but there are quite a lot of buildings etc. in Colombo and Trincomalee. You could try deleting some in the map editor (create back-up files first)?
The missions I am developing with this map, using 80+ aircraft and 30+ ships, including multiple carrier take-offs and landings, play pretty well at normal time - 40 to 60 fps (Nvidia 970, i7, triple screen, TrackIR); though there is significant drop-off at accelerated time - greater than x2 the fps count drops to single figures, but I can live with that.
What particular problems are you encountering?
best regards
Squashman