Hi there,
I still use .3ds models in anim8or for certain things though i generally export to Milkshape and convert to wavefront for use in UVMapper Pro.
You can use DBPro to convert your model to DBO:
load object "c:mylevel.3ds",1
save object "c:mylevel.dbo",1
This will convert your 3ds level to a dbo level and stick a copy in the specified directory. Takes a while to convert due to it loading up the 3ds version.
You should find that dbo versions load more than 10 times faster than their 3ds equivalent.
Also, depending on which modeller you use, check whether you can export to other formats. I generally use either anim8or (free and very good) or Milkshape (very inexpensive to buy).
Check out the modelling forum - has loads of links and useful tips for this sort of thing.
Good luck.