CIS slows down PC speed

Hello I installed CIS on my TOSHIBA laptop and the speed was awful. To open a simple website it needs seconds so I gave up. With Avira never happened. Or other AV. Maybe other users had this problem too.

Edit by EricJH: changed all cap title to regular case

I have Toshiba Satellite A300-1GN PSAGCE.
I use CIS with Avira free 1.5 year no problems.
System use 800 MB Ram on Windows 7.
Of course, latest CIS, Avira and other software and drivers.


Can you please provide a complete description of your system, including:

[ol]- Your computer model and CPU type (32 bit or 64 bit)

  • Operating System information (including Service Pack Version)
  • Report if you are using an Administrator account Or a Limited User account. Vista users please Report if you have UAC Disabled or Enabled (Optional if you post a Comodo Firewall Pro Configuration Report)
  • Actively-running security and utility applications (including whether you are using CIS antivirus in statefeul or on-access mode)
  • Brief description of your Defense+ and Firewall+ mode (Custom, Train with safe) plus mention if you modified any setting in ADVANCED section of D+ and F+ (Optional if you post a Comodo Firewall Pro Configuration Report)
  • Specific symptoms of the bug, and steps you can take to reproduce it (step by step). In your case, it may be helpful to look at the “processes” tab in windows task manager when you try to open a website to see if high CPU usage occurs with a particular process. Does your system reboot without your permission? Do you get a blue screen of death (BSOD)?
  • Specific steps you have taken to try to resolve it. Does the problem resolve when you disable CIS antivirus, defense +, or firewall? Does the problem resolve if you use a different browser? Does the problem resolve when you uninstall CIS?[/ol]

With the information requested above, the Comodo forum members may be able to resolve your issue.


This could very well be the same problem others have had for the past few months, ever since the update to the AV (engine or database) in November(?).

For me things have improved, but the system still seems to be slower than it was before.

There may be remnants of Avira and/or other uninstalled security software causing the slowdown. Try running the cleanup tool for any previously install software.

There’s an excellent reference listing at

I have TOSHIBA SATELLITE, XP S2, I didn’t get the blue screen, I’m using Chrome, my internet speed is 10 Mbps, my CIS had default settings (the free version), I have administrator account. I didn’t have any other AV or firewalls installed or remained in the computer. The system didn’t reboot without my permission and generally this was the single problem : the speed. After I uninstalled CIS the laptop got back to the previous speed which was ok. The computer was saving or writing something because the C: driver was running too much time when I tried to open a website. It’s true that I’ve had over 5 tabs opened but anyway, under the same conditions with Avira or ESET or other AV the PC works much much faster. Maybe I’ll try again CIS when I’ll have time to reinstall it. I use Avira…for now. Thanks for your reply.


Thanks for your response. Based on the information you provided, I am not sure what caused the slow down. I used CIS with Avira up until a few weeks ago and did not have a problem (so, it is unlikely that these programs conflict with each other).

Okay. When you install, please make sure you install the most current version. Perhaps reinstalling will solve the problem. If not, please see if the problem goes away when you disable each of the following: CIS antivirus, defense +, or firewall. Let us know how things go.


CIS + Avira’s fine here! :-TU

Spioneer, I was having similar problems with speed and loading issues after installing CIS. I discovered this issue about a week ago, after I decided to install Windows 7 64-bit. By chance I had to do a clean install of Windows 7 32-bit due to issues with a few older programs I use. And guess what? Same issue. Windows didn’t slow down until after the initial reboot required by CIS in both versions. I installed CIS before installing any additional programs or drivers. After some adjustments to Windows firewall, disabling both options, I rebooted and hadn’t had any issues since.

k9n-sli v2(Motherboard)/ AMD Phenom 9550 x4/ 4GB RAM
Windows 7/Admin Acct/UAC = Default

antivirus = stateful
D+ = default
F+ = default

Issue reproduced if Windows 7 firewall is active after initial restart required by CIS

  • Chrome/Firefox/IE = extremely slow/ time outs/ Not Responding
  • Overall system performance affected

Issue resolved if:

  • CIS uninstalled or (in my case)
  • Windows firewall disabled w/restart.

I believe that the problem is caused by Defense+. There are many programs installed on (uninstalled from) my laptop. I noticed that CIS didn’t response when I uninstall Visual Studio Ultimate. I believe that when a large program, which has a lot of executable files, is uninstalled, Defense+ would do something about the executable files in its trusted list. When those files are not there, it seems that the system will freeze.

I was doing some work on an old XP system and noticed two things. Installers using MSI installer, and I assume Visual Studio does, use lots of CPU cycles for longer periods of time; check CPU usage of msiexec.exe. Incidentally cmdagent.exe would also use quite some cycles but not as often or as many as msiexec.exe.