What does 不 at the end of a sentence (e.g. 更新速度可以快点不) mean?
yes, your translation is right.

可以…不 ～=  可不可以… 

Usually used to form an alternative question.

可以快点不～=可不可以快点?
这个可以吃不～=这个可不可以吃? Is this eatable?