Ubuntu 20.04 Performing Very Slow

I have just installed a fresh copy of Ubuntu 20.04 and I'm noticing that it is very slow. Firefox takes at least 4 seconds to launch and even sudo commands in terminal take around 2 seconds before executing.

I was using Ubuntu 19.10 before this and it was quite fast in comparison to this. I have not changed hardware nor have I installed anything that I didn't have before.

Is anyone else experiencing this? How can I increase the performance?

EDIT (Solution):

I have finally fixed this issue, instead of installing Ubuntu 20.04 directly, I installed Ubuntu 19.10 like I had before and then did a release upgrade and now everything is just as snappy before but with all the latest features. Not sure why the Ubuntu 20.04 fresh install was slow, but I'm happy that this has finally been fixed. Thanks for all the replies, they were very informative.

I also installed 20.04 and it became unbearably slow after I configured the system to use the proprietary Nvidia drivers (NVIDIA driver metapackage from nvidia-driver-390). If you did that, perhaps you can try reverting to the default drivers by searching for [Software & Updates] and then go to the [Additional Drivers] to using X.Org X Server. I also turned off animation using the Gnome Tweak Tool. Quite snappy now!

Here's another solution that I came across that helped me out. I disabled Secure Boot in my bios, and all of a sudden the fan cranked up and everything was MUCH more snappy. This feature checks if your drivers are signed.

Check out this post for more information:

Is it safe to disable Secure Boot?

While my fps rate and overall score is still relatively low on Unigine's Superposition benchmarking tool, it's still a step in the right direction for me after hours of fruitless research. Worth a try at least.

OS: Ubuntu 20.04

System: Asus ROG Zephyrus G

Card: GeForce GTX 1660 Ti Mobile

Driver: nvidia-driver-435 (proprietary)

Answer source: https://forums.developer.nvidia.com/t/geforce-gtx-1660-ti-not-working-in-ubuntu-20-04/153434/5

Note: I skipped step 3, and couldn't follow step 4, as I don't have the file he talks about.

If you have NVIDIA graphics, first thing is to check your GPU driver is installed properly, as has been suggested, and check that it is being used as preferred GPU and not any embedded Intel graphics.

Otherwise if everything is just consistently slow or choppy, it could be your CPU being down-clocked and frequency scaling is not working.

If you have Intel CPU and are using regular Ubuntu (Gnome) and want a user-friendly way to check CPU speed and adjust it, and even set it to auto-scale based on being plugged vs battery, try CPU Power Manager. If you use KDE try Intel P-state and CPUFreq Manager.

If you want to use terminal you can try install and use cpufrequtils package. There are many other approaches, some discussed here.