Very good question andyson. I spent alot of time looking at the 3 files mentioned above. Those three files, contain data on the files stored on your HD for your cache. As your cache increases the size of those files also increase.
Those three files, are loaded into memory when your browser starts. Also contained in those three files is data also. Just consider them a unusual zip file structure.
One file contains meta data for files less then 256 bytes. The next file contains data between 256 and 1K and the last for data between 1K and 4K. If you look at the files stored on disk for your internet, they are generally greater than 4K.
Surprisingly, the number of files actually stored in those three data files is large. Secondly, there is a utility that you can used to examine your cache, and determine how many times the data was retrieved, used over in game play. Surprisingly, very few are used more than once. The, HD photos stored in your cache is generally used only once. Thus, alot of wasted HD space is used.
The size of the cache files is directly proportional to the size of your cache.
Do a file search on your computer for those three files, and look at the size of those files. Then just use the guideline for HD speed, and you will get the general idea as to why the meter might stutter at an in-opportune time.
Secondly, if the cache gets too large, then those files will be updated more regularly.
Thus the answer on your question in retrieving data from the WGT server will not change much by increasing your cache size. The key, was how many times are the HD photos are re-used on a course by course basis. They are only used once 99.5% of the time.
Hope the explanation helps.