PDF Compressor is a tool which will try to reduce the size of any PDF files, without affecting how viewable they are.
The program is able to process multiple documents with one click. You can't simply drag and drop these onto PDF Compressor, unfortunately - the interface invites you to do that, but it didn't work for us - however we were still able to click the "Add" button and choose our test documents.
Compacting your select files is then as easy as clicking "Start Compression". Even our largest test files (20MB or more) were processed in a few seconds, output files sent to a new folder (there's an option available to overwrite the original files if you prefer), and a report displays the results.
And, well, initially they weren't too impressive. 11 of our 36 test files remained entirely unchanged, most of the rest lost under 10KB, even the four best performing files only shrank by 39-48KB (a maximum of 12%).
This was applying lossless compression, though. If you click "Compression Settings" and accept the option to reduce file quality, PDF Compressor will rewrite your documents in full. A few of the files stubbornly remained unchanged, but many now dropped in size by 20%, some considerably more.
There are also some problems here. We found PDF Compressor gave errors when trying to rewrite a few files, for instance, and the compression didn't work with some documents at all (one was reduced from 557KB to 3KB, though only by replacing the original content with four blank pages).
Still, if you need to distribute some PDF files - on your website, say - then it might be worth trying the program out, to see what sort of compression level you can achieve. Just check the compressed documents carefully, make sure they haven't been corrupted during the process.