Kaspersky Anti-Virus

thats also what I mean. the uninstall routine of those applications do not delete all files.
They delete most, and a kind of "reset" your station that is runs without the software but leave quite a number of unused files on the machine which may affect new installations and/or slow the machine down.

Example you install a new software, usually you get during the installation process a message "configuring windows/platform, software" (or similar).

In that process a lot of new files are created and somewhere "hidden".

When uninstalling the software (with its own routine or any other uninstaller), your machine gets re-configured, the actual software files deleted but many of the former new created hidden files remain unused on your computer