You gave us almost zero information so of course we have no idea. Rather than make a large list of possible causes, you should tell us a lot more about your configuration so that we can spot problems or narrow things down.
Look for patterns. Does this occur with all wifi connections? Have you tried wifi connections at work, coffeeshops and other places as well? If it is only on your router that should tell you a lot right there. What does your router log say? Even better, post a link to your router log or an excerpt thereof.
A snail's pace is a very vague description. Do a speed test and post that. Does the speed vary by the time of day? If this is a problem with your home router, try moving the router or changing the default channel. What mode (a,b,c,n) are you connecting in? How about a screen shot of your phone's wifi settings? You need to tell us a lot more about your phone and give us a detailed, step by step description of what you've tried so far if you are looking for good answers.