Why do software installation or updates always go very fast up to 90% complete, then the last 5-10% takes so much longer?
In: Technology
That last bit is where the installer is registering keys in the registry and other areas and basically uninstalling itself.
Depending on the access the app you’re installing requires, that registration can be pretty time consuming (from our point of view).
This is *also* why the installation of many programs needs us to reboot our computers. Until that’s done, all the registration the installer did isn’t *finalized*. 9/10 it won’t cause any problems If you use that program without rebooting, but *sometimes* that 1/10 can seriously fuck your system up.
That first 90% is you dumping a moving box all over the floor
The last 10% is putting everything away nice and neat
Basically, the computer has no idea how long it’s going to take. It knows there is X number of steps and how far a long It is for each individual step and its going to try and predict how long it’s going to take based on the information it been given by the dev inatally.
There might also be a psychological explanation as well but I’m not sure
Edit: [tom Scott explains it so much better](https://youtu.be/iZnLZFRylbs)
The progress bar is nothing but a guesstimate. So the first 90% is guessing, the last 10% is the installer realising it is way off.
It’s not a linear process but to make things “user friendly” interfaces are made with an assumption that things indeed are linear.
The code that shows you “% done” only knows about the tasks that need to be done, not how long each task will take. So if the early tasks are very simple tasks, but the latter tasks are very complex tasks, it will appear to slow down as you see a % done being calculated.
You shouldn’t really listen to anyone here. The answer is that it’s implementation dependent. Maybe the engineer wrote it so that there are four steps of 25% each. Copying files is maybe step 1 and is super fast. Step 2 is a big database operation and is slow… etc.
Maybe the steps are totally fake. Maybe there is a simple timer that moves the progress up 10% every second until 99% where the last percent is actually dependent on something.
Its completely unique to the person who programmed it or a commonly used installation software.
It’s also possible the installer in question has a step at the end that is bottlenecking but the progress meter doesn’t factor that in. Maybe you downloaded the package to ssd and it’s not trying to unload into a HDD. Really could be anything
Sometimes Install percentage is based on the number of files that have to be installed and or modified. The large lag is caused by a large files that have to be copied and in some cases unzipped.
It’s like someone is counting out the $100 they are giving you with the first $90 in 10’s and 20’s and the last $10 in loose change.
Similar to how you go to a car boot sale / rummage sale with all of your stuff. That’s normally quick – then you have to unpack and place all of your items onto a table which takes time.
The same applies for software installation. The process of getting to the point of installing is quick, so is the first part of your computer working out what to do. Then small files need to be moved into the right places, computer updates system registry and then cleans up.
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