Perhaps an important information for as many critics:
EVERY security software has an effect on the performance of a system! It does not run any security software on each system, but there is the 30-day trial versions to find out. If G Data on my system running properly, it has to run just as easily not necessarily on other systems with identem operating system. Here applies Trial & Error!
Herzugehen here and evaluate the negative software is not running on a system is absolutely wrong, this one would have been able to notice during the 30 day trial period. For this, the software can be downloaded for free from the manufacturer's homepages; no one is forced to buy!
Unfortunately, many believe, "much security software helps a lot." But this is precisely not the case! Only one anti-virus software be installed with an active background guard on a system, as this will cause system crashes or system errors. Just remains of a previously de-installed security software can remain in the system, then the current security software hämmt / blocked or the system to crash. To avoid this, each ordinary security software vendors a tool with which you can rid the system of this installation remains after uninstallation. With G Data is the AV Cleaner (available on the homepage of G Data in Downloads menu - Tools).
A security software reaches deep into the system and can therefore be seen as a critical software that must be tested properly on a system. Sometimes fast one and can install the other security software backfire. Here must be exercised with caution (eg backup before installing).
On my systems G Data has been running for a few years without causing problems. One or the other security system, however I brought not to run.