Shridhar Gowda is correct. When you make a code change, just build the Project and transfer only the
dlls
present in the
bin
folder, which are updated by the Build.
One very easy of doing this is to use
Publish Feature from
Visual Studio. When you hit Publish, it would give you the files or dlls that are currently updated. You can save it to a Folder and then Transfer manually through the FTP Client or Publish directly to the FTP Folders.
Refer -
How to: Deploy a Web Project Using One-Click Publish in Visual Studio[
^].