These are normal. And notice that all of the processes shown in your screenshot except one Firefox.exe are using no CPU cycles. For that reason, I don't think that anything shown in this screenshot is the reason for your system "running slow and seems
messed up."
Click on the button in Task Manager to "Show processes from all users" and you'll probably find some processes running under SYSTEM, LOCAL SERVICE, NETWORK SERVICE, or one of the other system accounts.
More than likely, if this slowdown happens when you first turn on the computer, it is Windows Update checking for updates, your antivirus program doing a system-wide scan, and other installed applications also checking for updates. You can configure most
of this sort of activity to not happen automatically on startup.
You also can run Resource Monitor (click button on the Performance tab of Task Manager). This will give you a better idea of what processes are using which resources (CPU, RAM, disk access, network).
Firefox has separate firefox.exe processes for each tab that you have open in Firefox. For example, see
https://support.mozilla.org/en-US/questions/1147868 That explanation was from quite a while ago, and although the default is still 1 process per tab, I don't know if the suggestion for disabling that behavior still works.
I suspect the the multiple Dropbox.exe processes are OK, but the explanation I found from a couple of years ago that there was one Dropbox.exe process for each Dropbox account that is actively signed on doesn't seem to be the last word on the matter. Here's
a more reassuring response (although not very explanatory) from the "solution" in this thread:
https://www.dropboxforum.com/t5/Installation-and-desktop-app/Dropbox-has-two-entries-in-my-PC-Startup-Why/td-p/181091
Thank you for contacting Dropbox!
I can confirm that it is expected to see multiple Dropbox processes in task manager when Dropbox is running. The Dropbox application needs these additional components to monitor that everything is running correctly and that the desktop application is always
healthy and up to date. The additional processes should consume a negligible amount of CPU and memory resources. If they are causing any performance issues on your computer please let me know.
If you still have doubts, ask in the Dropbox forum.
Nvidia Share.exe is also expected to have multiple copies of the process running. See
https://www.howtogeek.com/343120/what-are-all-those-nvidia-processes-running-in-the-background/
The NVIDIA Share processes (NVIDIA Share.exe)—and yes, there are two of them—also appear to be part of the GeForce Experience overlay. This makes sense, as the overlay contains sharing features for sharing video clips and
screenshots of your gameplay on a variety of different services.
When you disable the In-Game Overlay from GeForce Experience, these processes will also vanish from your system.
However, if you end both NVIDIA Share processes and then press Alt+Z, the overlay will reopen and you’ll see that the NVIDIA Share processes are now running once again. This seems to demonstrate that the ShadowPlay Helper listens for the keyboard shortcut
and then hands off to the NVIDIA Share processes, which handle the overlay.
nvcontainer.exe is another Nvidia process discussed in the same How To Geek article.
cis.exe is Comodo Internet Security. Multiple instances are normal. See the post from "EricJH" here:
https://forums.comodo.com/firewall-help-cis/how-many-cisproccesses-is-running-in-windows-task-manager-t94159.0.html
If you're still curious about the others, just run a Google search for << multiple xxx processes >>