There are several grades/speeds of WiFi - a/b/g/n. The fastest is 'n'. Check if your computer AND access point (router) are both using that. Also, the distance from the access point (AP) to the computer affects speed tremendously. There are high-gain antennas (if your AP has an external antenna/antennas) that can improve that factor. Also, the communication channel that your AP uses can be important. If there are other WiFi AP's in your area that use the same channel (default == 6), then that will also affect your available bandwidth - set it to a channel that is not being used by others in the area.
A final note - if your AP is physically distant from your computer (such as at the other end of the house and on another floor), then you might consider getting a WiFi repeater - effectively an AP that re-broadcasts the signal from the router to your computer, and from your computer to the router.
Also, I agree with Rev.Jim. Software won't do much (or anything) to fix these issues. FYI - I am a senior systems/performance engineer with a tier-one mobile phone company and work with this stuff for a living. I also used to teach AT&T techs the fundamentals of wireless tech classes, including WiFi, cell, etc.
The answers provided are indeed correct. There is no "real" software booster. However, you could consider upgrading your wifi card, whether it is a laptop or desktop, or your router. There are too many scenarios that could possibly assist in boosting your signal, however there would have to be more information provided.
Rubberman provided excellent guidance with little information provided from your post, however there is a new standard just released named IEEE 802.11ac. This now surpasses 802.11n in throughput, but it comes at a steep cost.
As a final note, you may have a slow internet connection, in which case your wifi is not the issue. The router could be in the same room, with a top of the line 802.11ac router and card. If your ISP connection is 256kb or even 1.5MB, at some point you will most likely want to forcefully toss your computer against a brick wall, or run over it with your vehicle several times.
There are many variables with your problem, if you would like to provide more information, we can assist you to the best of our abilities.