There are a lot of things may affect the connection speed of you WIFI. The connection speed between router or AP to your PC or laptop. One of the most important fact is the channel. For 2.4GHz, there are 13 channel. 20MHz each channel 1 : 2412MHz 2 : 2417MHz 3 : 2422MHz 4 :
WiFi IEEE 802.11b has a very limited channel (depend on country). In vary pack area with many WiFi Access point not all channel can be use at the same time. In North America, US State and Canada only Channels 1,2,3,4,5,6,7,8,9,10 and 11 are available for usage. In Europe Channel 1,2,3,4,5,6,7,8,9,10,11,12 and 13 can be use.