Poor performance and damaged battery after Tahoe 26.2 upgrade on Macbook air m2

I see you have Avast security installed. That can cause problems, plus Avast has been caught at least twice selling user's personal information. Anti-virus apps, cleaning/optimizer apps, and third party security software are not needed on a Mac. These types of apps usually cause more problems than they solve by causing system instability & performance issues because they interfere with the normal operation of macOS at a very low level. Uninstall Avast and any other apps I have listed by following their developer's instructions.

macOS already has great built-in security as long as users also practice safe computing habits as outlined in the following article:

Effective defenses against malware and other threats - Apple Community

Since you have Avast installed, you should run the third party app EtreCheck and post the complete report here so we can examine it for clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

Dregavero wrote:

I just want to add that I've had Avast installed since I've purchased the laptop

Below are the EtreCheck report

I noticed AVAST elements had been installed into your Mac back in mid-2025, before Tahoe came out. Unless you have updated to a Tahoe-compatible version of AVAST, there is a not-insignificant chance what you have conflicts with Tahoe. Of course, there is really no legitimate reason to be carrying the heavy baggage of an antivirus on a Mac (and it is heavy baggage), given that the MacOS is placed in a sealed, readonly snapshot volume that can only be accessed and modified by certified connections to Apple's servers (you can't modify it yourself). Even if you wanted, you can't place a virus in that MacOS. So why drag your Mac down with AVAST, it is checking every byte and bit that comes to or leaves your SSD, as well as every byte that comes to/from your Mac via the internet and your local network. This results in significant additional overhead. But for what? While you can install malware on a Mac by following careless practices, it is fairly easy to avoid and you don't need AVAST to check for malware (in fact Etrecheck can do that up to a point).

Speaking of slowing a Mac down, Etrecheck reports that your disk read/write speeds are very slow:

Write speed: 1347 MB/s

Read speed: 2685 MB/s

You have an M2 laptop, this is a modern and very fast and capable Silicon Mac; yet my ancient 2019 Macbook Pro with a 2.3 GHz 8-Core Intel Core i9 processor (old technology) which is probably at least 5x slower than yours, but it gets 3000 MB/s for both read and write.

I do realize you have only 8 GB RAM and that it is not upgradable, so you have to work with that. But it is hard to imagine how a modern Mac can function well with such minimal memory; what happens is that 8 GB gets used up rapidly and then the Mac has to page in and out to the disk, but with AVAST insisting on checking every bit and byte written to and read from the disk, this drags down the Mac in a compounded way.

You also have a kext that has some custom driver/software for Samsung drives

SamsungPortableSSDDriver.kext - com.samsung.portablessd.driver (2.0.0 - SDK 11)

this too can slow down your Mac if this driver hasn't been updated to be compatible with Tahoe. Frankly, installing custom kexts for these external drives does not add value and can add harm. Apple has capabilities built in to the MacOS to manage all drives and when third party disk tools are installed there can be a tug of war between them.

Why are things worse after Tahoe? If you have questionable systems extensions installed or items incompatible with Tahoe, that is what happens. Also, Tahoe changed some things so compatibility is essential.

I think once you uninstall Avast, most of your performance issues will be gone.

While Google Chrome is resource intensive, if you don't have a lot of windows/tabs open, then it probably won't be too bad. There are a lot of other third party browsers based on the Chromium rendering engine which should be as compatible to sites & services as Google Chrome, but may be a bit less intrusive.

The EtreCheck report shows about 12GB of Swap being used over the 19 days since the system was last restarted. You may want to keep an eye on the memory usage in Activity Monitor. If the memory pressure graph in Activity Monitor is in the red, you system does not have enough memory for its current workload. If it is in the yellow, then the system is borderline on having sufficient memory. If the Compressed memory or Swap are in the GBs (even if the graph is green), then your system may not have enough memory for your workloads. I can tell you that 8GB of system memory is only good for the most basic tasks.

It is hard to believe Apple still sold systems with just 8GB of memory with the M2 Airs. This can easily be another bottle neck for the performance issues. If low memory is the problem, then you either need to adjust how you use this laptop to minimize the number of open apps and windows/tabs, especially when running the more memory intensive workloads......or you need to purchase another computer with at least 16GB or 24GB of memory.

Sounds like you have some excessive CPU activity or perhaps even a failed process.

Open the Activity Monitor and look at the Energy and CPU sections.

Activity Monitor User Guide for Mac - Apple Support

Take a few screenshots and post those back to this thread.

Take a screenshot on Mac - Apple Support

Dregavero wrote:

You can see I started using the laptop at 9 pm and in the following 5 hours it lost 44% of the battery, while just staying in the brower.

That browser appears to be Google Chrome. Chrome is a notorious resource hog on Macs. Installing it also installs multiple ‘helpers’ from Google that run in the background, and their purpose is not to help you but to help Google (keep in mind that Google’s primary source of revenue is using your data to drive targeted advertising). Even if you aren’t running the Chrome app, those system extensions are always running in the background. I’d recommend deleting Chrome and all related components.

https://chromeisbad.com

If you are looking for something other than Safari, consider Firefox or Brave (the latter is based on Chrome code but without the Google baggage).

You're welcome.

Immediately after a macOS upgrade or update, the system has some background work to preform which requires a lot of energy. Depending on the Mac, the stored data and third-party App's, that background work can take anywhere from 1 hour to 1 day to complete.

This is why it is recommend that you have laptop on the charger when preforming updates and upgrades.

In addition, you should always run the laptop on the charger when there is an available AC outlet.

At this point in time, that background should be complete and things should be settling down.

If not, Start up in Safe Mode followed by a normal Restart and test for a day or two.

Start up your Mac in safe mode - Apple Support

Activity Monitor may give a more complete picture if you change its "View" option to :All Processes."

Allan Jones wrote:

Activity Monitor may give a more complete picture if you change its "View" option to :All Processes."

Good catch Allan.

I still only use light Mode on my Mac's and in the Dark Mode screenshots, it is nearly impossible for me to see highlighted selections and fine details.