In good speed network, packing all *.js into one *.js may improve the performance of loading the *.js.

For one of my page, I have about 150 *.js file, which total size is about 400k. When loading with only one *.js file, it takes about 800ms rather than the older 2000ms in Firefox 1.5.

For bad network environment, other factor should be considered in deciding whether *.js should be packed into one *.js file or not.