CCleaner or Disk defragmenter

Thanks for the tip. But how long will the defragmentation be?

Forever. When you delete files a placeholder remains where the file used to be. All this means is that it takes a little longer to find things. Defrag helps to organize files much like pulling it would in a filing cabinet. It is maintance so can be done periodically with computer useage.

Actually, Bluedoll & sinnedsejatnom, it's more accurate to say that, when you delete a file, all that happens is that the index entry to that file is marked as 'Deleted' (in fact, the index entry is changed so that it marks the file as 'in the Trash Can'). Nothing else happens at all: the file still exists on the disk and the index entry is still there. When you empty the Trash Can, the index entry is changed again and the indexing system (NTFS) says, effectively, "this space is now vacant" (the file's data is still physically on the disk at this point and could easily be recovered). When new files are written to disk, they may partially or completely overwrite the area where deleted files were. Because new files are unlikely to be exactly the same size as the deleted files, the space where old files used to be may not be large enough for all of the new file, so parts of the file may end up in physically different parts of the disk. Imagine a (mad) librarian taking old books off the shelf to make room for new ones. If the new book is fatter than the old one and won't fit in the space, the librarian just rips the book apart and puts one part in one space and the other part somewhere else, making a note, of course, on where to find the different parts of the book when it's needed. As you can imagine, after a while using this system, especially when the library shelves are almost full, it takes longer and longer to find all the parts a book has been split into. What defragmentation does is to physically reorganise the 'shelves' and put all the scattered parts of the 'book' back together.