Hi,
FlexCel is divided in modules, so for example adding "just" xlsx support won't add the libraries for pdf exporting. But the problem is, xlsx support is one of the 2 things that take a lot (and really a lot) of code (the other is recalculation). The reason why xlsx takes so much code is because the spec is huge and very verbose, and also because we had to implement things like our own zip support and xml readers and writers. The reason why recalculation takes so much is because we support about 300 functions and each one of them has to be implemented (and while some are simple like =sum, some others can be quite complex on their own.
What we could do to reduce a little the size is to allow a way to remove recalculation, so the exported file wouldn't be calculated when you save it, but Excel will calculate it anyway when you open it. But well, we still have to do a lot of things in FlexCel (like as said pdf and html export) and right now we re focusing in that. If we do make the recalculation optional, this will be after we finish those things. (And we will do it only if it proves that size is reduced in a significant way, if after we do it we verify that it just adds complexity, then it might not be done).
We do have plans to study size and how it can be reduced in the future, but as said, priorities right now are to get all the missing parts working. And it might not really be possible, as latest delphis tend to blow the size of any part of code a lot (and yes, we do suppress the extended RTTI)
About the actual sizes, compiling in release mode (please never do a size test in debug, Delphi can throw 20mb exe files in an empty files with a form and some buttons), the numbers for the demo app are:
Without FlexCel: 3.395 mb
With FlexCel: 9.957mb
This number isn't that important normally, since you don't really care about a 6mb package in a disk with 1tb, but what you normally really care about is the distribution size (which is zipped). So the zip numbers are:
Without FlexCel: 982 kb
With FlexCel: 2.388mb
So we are speaking about a 6.5mb size increase in the disk, and a 1.5mb in distribution. I wonder how much removing recalculation could shrink this down. But well, otoh, when you compare it with .net it is huge (the full FlexCel.dll for .net with pdf export and everything is 2.356mb, compressed to 696kb ), but if you compare it with Excel itself then it is tiny (we are speaking about hundreds of mb if you have to install Excel to do OLE Automation)
As said, we will be investigating if there is something else that we can do to reduce size, but with low priority. Right now we care more about having everything working.