Creating New Files

In my opinion there isn't any real good reason to use year end copy, and lot of reasons not to use it.  Almost everyone that thinks it will benefit them misses the fact that Quicken is a database program and as such more transactions usually doesn't equate to slower performance.  The exception seems to be in the investment accounts, which I think is because they calculate the "lots" on the fly and other GUI slow downs.  The year end copy function doesn't touch investment accounts because of all the complications you would have if you have lots that aren't completely closed.  As such the function almost never provides any performance benefits.

Note that Quicken doesn't even read in an account until you access it, and then once it does it, caches that information in memory.  That is why the first time you access an account during a session it is slower than if you come back to it later.

Now you could use the copy function or start a new file altogether to really strip out the investment data (and have to deal with starting over or reconciling that you might have just thrown away the "buys" for some securities that you still hold).

If the actual size of the QDF file is a concern than most likely you are using attachments and they are what are making the file so big.  If you want you can use the copy function with the option to include the attachments turned off to remove these.  This won't improve the performance because again these aren't read unless you access them.