AV-Comparatives: Performance Test - October 2017 http://chart.av-comparatives.org/chart1.php?chart=chart4&year=2017&month=10&sort=1 https://www.av-comparatives.org/performance-tests/
Avira's score : It's the score Avira does deserve.... Oct 2014: Avira Impact score = 2.3 points (2nd). Oct 2015: Avira Impact score = 2.3 points (Top ranked). Oct 2016: Avira Impact score = 0.3 points (Top ranked). Oct 2017: Avira Impact score = 8.5 points (Position: 10th out of 21 products).
In my experience ESET is the lightest security out there, version 10 doesnt impact my system performance at all; Avast has a very low system impact on my system too, the rest is average.
Trend Micro AV, for example, is heavy as hell on my old machines with Windows 10, whereas Windows Defender is light as a feather. Go figure.
That's my experience too with Trend, but I've never experienced Windows Defender being light on old hardware.
Maybe it's because the hardware. My laptop is a 2006's Vaio with 1.46 GHz Intel Pentium T2310 dual-core processor, 2gb ram. The other is a 2010's built up desktop with a similar 2.0 GHz Intel dual-core processor, 3.5gb ram. Both with the latest Windows 10 Pro 1709 (CU).
That's a very slow CPU, and I've seen high CPU at times from Windows Defender and the resulting slowdowns, with faster CPUs. However, I have not run build 1709 on any of these computers yet.
ive been saying for years how heavy trend was and so many were like no way its sooo light. i have yet to have any systems it runs that light on. sure some with top shelf hardware then yeah but it sure is still noticeable.
I haven't seen Trend on a systems with fast processors, but on the systems I have seen it installed on it does cause noticeable slowdowns. As a result, I often replace it with something lighter, so the customers computer runs faster. Also, I've seen a few computers which have a corrupt installeof Trend on them, where it is installed, but will not run.