Not quite smooth installation - it remains a queasy feeling

F-Secure Anti-Virus 2015 promises a comprehensive protection from viruses without the PC slowing down.
The financial framework for installing PC runs on Windows 7 and Avira made so far for the security of the system against malware threats. For many years, has also worked very well, but that the computer lately became increasingly slower - he is no longer even the latest copy - I wanted to try and see if a purchased software requires less processing power.
The PC still has a DVD drive, so I could install in 2015 directly from the CD F-Secure Anti-Virus.
First of all a tool for checking the computer is started on any existing malicious programs, this review took me about 15 minutes, then followed by the actual installation of the program.
During this Searched for incompatible software and promptly criticized the presence of Avira. After my approval, however, this program should be removed from F-Secure, which has again taken just under 15min. During installation, the license key still was interrogated and an email address for registration requires further data were not required.
Finally, carried out a restart, and it showed that Avira not disappeared, but both the program icon on the desktop and in the taskbar were still present. I so I have to ask what has previously taken 15 minutes time; uninstalling Avira not anyway.
With two antivirus software, my computer, however, showed slightly overwhelmed and was so slow that I had to shut it down and restart it. After this restart at least the symbol of Avira had disappeared in the taskbar; on the desktop and in the programs it was still there, so I had to remove it ultimately manually.
To have happy, now taken all the hurdles I called on the F-Secure program by the icon in the taskbar, but I was promptly shown that the virus protection is not working properly and the computer must be restarted.
After a short wait time, however, this indicator will disappear and a check showed that everything was in perfect order.
Unfortunately, such a bumpy installation leaves at least for me not to feel superior security, particularly Avira - although a free program - is easier, faster and without such antics could install.
The performance of the computer, I have to admit, however, has improved. Especially the startup runs noticeably faster since F-Secure Service pushes, under Avira everything went very tough and leisurely.
Nevertheless the bad feeling that after the installation idiosyncratic perhaps something is not working as it should ...

Update 9/12/2014:
The computer will only run faster when F-Secure does not double haunts in Task Manager, but what it does often times.
Then we have to wait, wait, wait, because the crate then runs tough as chewing gum. Only one of the two processes to quit again accelerated the PC. However, then comes the annoying message prompt to restart the PC, because the program is something wrong.
Yes, I think because so wrong a lot.