Response.ContentType = "text/javascript" or Response.ContentType = "application/x-javascript"

Hi experts,

I am currently trying to make our web product quicker by removing all the dynamic arrays, javascript calls which are built into the page into external files which so far I have got the from 475,000 bytes down to 53,000 bytes.

The page is ASP so is fully dynamic but it is sometimes still a bit slow expecially when the dynamic arrays are building (the arrays are used to filter locations assigned to buildings (so can have about 50 buildings each building can have between 50-200 location so could be upto 10000 array)). I would like to cache them until the users session is up so looked into the content type but for Javascript there seems to be about 3 different ways from what i have seen on the web and a couple which have been accepted as solutions on EE

Can some one please explain the differences (if there are any)  and which one is best to use from the following:

Response.ContentType = "text/javascript"
Response.ContentType = "text/js" (seen this on the web but not sure it is actually usable)
Response.ContentType = "application/x-javascript"

Thanks in advance

FSIFM