I can't diagnose what, if anything, is wrong with your computer from the screenshot you've posted. The fact that AVG detected and quarantined Trojans on your system would suggest to me that, yes, it would be a good idea to have a malware removal specialist check your system in the in the Virus, Trojan, Spyware, and Malware Removal Logs board. It normally takes a few days for a specialist to be assigned to your case and review your diagnostic logs, and while you're waiting you can monitor your CPU consumption while automatic Windows Updates are disabled. Try not to make any major changes to you system after you've submitted your diagnostic logs for analysis.
Just a few random observations:
I see your Resource Monitor and Process Explorer both showing 17% CPU consumption, with most of that activity consumed by a process called node.exe. I can't tell if node.exe is associated with legitimate software or malware from the information in your screenshot (see my hint below about Process Explorer). The 59% CPU consumption you're referring to was probably just a temporary spike in activity you captured in your screenshot.
DBBBleeping CPU 17 Percent.png 19.25KB
When you look at your CPU consumption on the Processes tab of Task Manager, by default the list only displays the processes running under your own user account. You must click the Show processes from all users button to see all the processes running on your computer, including those running under user SYSTEM (i.e., your Windows operating system) like the System Idle Process. Your "missing" CPU could be consumed by the host process svchost.exe or some other process running under SYSTEM when Windows Update is running in the background.
Vista Task Manager Show All Processes.png 12.11KB
See the Ask Leo article What is the System Idle Process and why is it using most of the CPU? It's normal for this idle process to account for most of the CPU activity on your computer. The CPU consumed by the System Idle Process is basically 100% minus the total CPU consumed by all other processes running on your computer (e.g., 100% - 59% CPU consumption = 41% allocated to the System Idle Process).
You had 140 processes running on your system that consumed 71% of your available memory (RAM) when your screenshot was captured. The hardware specs shown in your user profile are very similar to my own machine, and just for comparison I normally have about 60 processes loaded into memory that consume about 50% of my 3 GB of RAM. A portion of your system resources might be consumed by malware or PUPS, but I'm guessing that you have quite a few legitimate (but unnecessary) programs that start automatically when you boot up your computer and degrade your system performance by consuming CPU and memory. I'd suggest you review all your startup programs and see if there are any "optional" software programs loading into memory at boot-up that don't really need to be configured to always start with Windows.
One useful tip for Process Explorer (PE). If you don't see a column in PE named VirusTotal, go to Options | VirusTotal.com and ensure Check VirusTotal.com is enabled. Then go to View | Select Columns... and ensure that VirusTotal is selected. When VirusTotal integration is enabled, PE will submit the SHA-256 hash (digital fingerprint) of every process running on your computer to the VirusTotal.com website for analysis by approx. 50 different malware scanners (e.g., AVG, Kaspersky, Norton, McAfee, Malwarebytes, etc.). A low detection rate (e.g., 0/56) means the file is safe, but a high detection rate (e.g., 5/56) means that the file is suspicious and could be associated with malware - see the Windows IT Pro article Process Explorer v16.0 Integrates VirusTotal. Clicking the link in the VirusTotal column will take you to the full report for the process on the VirusTotal .com site - see the report <here>, for example, for the "safe" firefox.exe process for my Firefox browser.
PE VirusTotal Integration.png 49.41KB
32-bit Vista Home Premium SP2 * Firefox v49.0.1 * NIS v126.96.36.199 * MBAM Premium v2.2.1
Edited by lmacri, 04 October 2016 - 06:04 PM.