The processing of tags and posts often too much time to be run every time again when a tag cloud is rendered. Tag Groups Premium therefore uses caching on various level. That means that once it has finished processing, the result is stored for the next time so that it doesn’t need to do all the work again.
Some forms of caching are always enabled. In order to benefit from the maximum speed increase, please make sure that object caching is enabled in the Tag Groups Premium settings. Try first “database”. If you don’t see any improvement, try “file system”. The speed improvement should be noticeable starting from the second time you load the page after saving the settings.
The cache is automatically emptied when you make changes that require to rebuild the cache. You can also purge it manually on the same page in the Settings. Then again, you need to load the page with the tag cloud one more time to fill the cache until you see the speed increase.