While there is some debate on the subject, it is generally accepted that chlorine tablets do in fact dissolve faster in warm water. This makes sense when you think about it – after all, hot water is known to speed up chemical reactions.
So if you're looking to get your pool ready for a swim as quickly as possible, adding the chlorine tablets to warm water is likely to give you the best results. Just be sure not to add them to water that is too hot, as this could damage the tablet and make it less effective.