Doing a low level format is even worse for an SSD than defragmenting it, because every bit of the SSD will be written on.
Opinions about defragmenting an SSD differs greatly, it just depend on the situation. In my case, when my SSD was less then 200 MB free, it can give you free space again. On this moment my SSD is used for a little over 52000 hours and it has no faults. An SSD can be written a few 1000 times at the same place again before that place gets worn out.
But what I also experience over time is a slow down, just like you do. As a rule of thumb, every 10 months I do a complete new installation of the Windows software (remember I am on Windows), which prevent for me the slow down.
Depending on the use of your computer, you will experience a slow down which is not your SSD but the applications and utilities installed and running on your computer. Maybe disconnecting your computer from the internet, switch of Anti-virus and anti spy/malware applications and then see again.
You are mentioning Firefox slowing down. Since I think something less than two months ago, I also am not so satisfied with Firefox anymore because it is slowing down too. Nevertheless I found out that my computer/firefox is infected with a very nasty malware which is blocked by MalwareBytes. Every time I visit another website or page, that malware becomes active and I get a message from MalwareBytes it is blocked. It tries to call home to an external website to send the information it logged on my computer. Sometimes the keyboard is very unresponsive, also when no browser is open. I tried everything, followed a lot of procedures to remove it, however everything failed. It seems to me I have to reformat my SSD again and install a new Windows OS.
@Markus Winter
As a translator, I do not have to know the internal workings of the applications I translate. I just receive an .lng file which I use for the translation. What use would it be for me, to know the inner workings of the applications I translate. we are a virtual assistance business which finish the projects we receive mostly within a very tight deadline. Many times we work with 3 or 4 people on the same project, without really knowing each other. On the higher level, there is a secretary (believe me she is very much multi-tasking/skilled and bossy) which does the management, administration, keep track of the timelines, divide the workload and overview the projects/people working on them. We receive the wishes/specs of our clients and all people involved do their job in conjunction with the others. At the final stage, everything is combined in the project, final checked and send to the client. That is how we work. I did not want to insult you Markus, just shared my opinion and impressions. Who am I to judge about your skills? Despite the fact, I believe our personalities and professional skills match each other to work succesfully together, we hardly know each other so it is hard to judge each other. Anyway I do not judge anybody, I just don’t like it. You are a friendly, very helpfull person with a strong temperament which surface from the moment somebody disagrees with you. Your positive gifts far outweight your strong temperament which makes you the man you are which is good. Can we now go back to the subject of the OP?
Maybe your computer is infected with the same malware? I cannot tell what to do on Mac but I am afraid to get completely rid if it is the same malware, you have to do a clean install. At my place with Windows, everything I tried failed and believe me, it is a lot. Normally, I can remove spy/malware/ virusses without any problems. Regretfully, this malware seems to beat me or I get lost somewhere.
The malware which is blocked at my laptop is :
WARNING : FOR YOUR OWN SECURITY DO NOT CLICK THE FOLLOWING LINK,
OR YOU ARE RISKING TO BE INFECTED ALSO!!!
f.asdfzxcv1312.com
IP : 198.7.58.86
Port : 12613
Type : outbound
Process : C:\Stargate\Firefox\App\Firefox.exe
If I would not have installed MalwareBytes, I would not even know that this virus is present. Still, even Malwarebytes does not succeed in removing it. I have no idea how I got this malware.
Did you try Garbage collection on your SSD? This can give your SSD better performance, better than defrag. In Windows 7, get a utility which issues a Trim command or copy your data and then do a secured erase, after that then you copy your data back.
Hope this helps.
Chris