In this paper, the impact of background traffic on TCP performance is examined over indirect and direct routing for mobile computing. Furthermore, the performance is examined for broadband and narrowband mobile user. We design four topology scenarios that describe the relative difference between the indirect and direct routing in the length of routing path (number of hops). The paper concludes that with broadband access the effectiveness of TCP performance improvement of direct routing over indirect routing not only depends on the relative difference of routing path length between the two routings but also on background traffic load - the higher the background traffic load is, the more apparent the effecttiveness is. Furthermore, it is shown that the location of bottleneck for data transmission has a significant impact, on performance improvement. The bottleneck within wireless local area usually consumes the performance improvement created by the direct routing.