Sorry for my reply. I am only an F-Secure user (their home solutions).
Maybe there will be official response from F-Secure Team; but just as a discussion between community users:
- how it connected to F-Secure solutions? Or which one package there?
If it is something like branded F-Secure Freedome VPN - likely that some differences with speed are expected.
If it is branded F-Secure Internet Security / SAFE - I do not think that it should reduce your network speed too much.
If even it is branded F-Secure SENSE... possible to doublecheck next Community board:
what if such concern is discussed already.
Good if you will back with reply. Or will explain more about your concern.
And sorry for my reply.
Like @Ukko has suggested, please let us know which F-Secure product are you referring to. Please provide more information on your issue with the F-Secure product.