speed dos on xp

I have a dos program running on xp – 1.4 ghz 256 MB, plenty of hd. It is much slower than on our 486 with win98. Is there anyway to speed it up? The program is proprietary, calls up several smaller programs. Basically it calls a program that dials out to another phone line and connects with another system and then transfers information while running locally. Any ideas? Since it works fine on the old pc I am guessing it is something with xp but haven’t found a ton of places to adjust performance as I am new to it. Thanks!