I noticed in FMP 13, the cache size has a default value of 128 MB.  I have a lot of memory to spare, so I tripled this.  What does this "help," and are there any risks?

You are talking about the FMP client right, not the server?

 

Upping the cache on the client side will speed things up, the penalty is data loss if your client crashes.

Yes, client, sorry. Our clients do not crash, but my assistant has a relatively flakey Internet connection. Would data be lost in that scenario?

Our clients do not crash

 

Ha!  There are only two kinds of people: those who have lost data and those who will.

Computers crash.  It's just a fact, and it comes in many forms.

but my assistant has a relatively flakey Internet connection. 

 

Absolutely.  When FM client (FMP, FM Go, WebD,...) looses its connection to FMS it can not push what is in the cache to the server.  Data will be lost.

Its a fine balance.  If you evaluate your connection to be stable you can up the cache to get better performance. 

I'll probably keep the default of 128MB for her, then. My Internet connection is incredibly solid (overly priced business account) that hasn't gone down in 1-2 years, so I'll probably keep mine higher. Now, if Apple sees fit to sell a laptop (preferably 17") with 32GB of memory . . . . .