[Razor12911]

Firstly 140GB is the space that is needed, but let me run though everything you can see what we are dealing with here.

First of all, 4 hours was just a simple example because this is rarely achievable on HDD, some take 18 hours and 4 hours is something you get if running on SSD unless if you're using something like pzlib or a more reworked reflate.

Secondly, 45GB of the data is inflated to 90GB and that makes it 90GB of thousands of raw files.

Lastly repackers for some reason never let srep be free to choose how much memory it should use by itself by using cls-srep which has a 2GB limit because of x86 restrictions, which means a 8GB srep virtual temp needs to be created even if the person who is installing the game has 32GB, will still be restricted.

When you equate all this IO, Firstly the data that is inflated is compressed to something like 18GB.
lzma decompresses, that's 18GB read, and IO write does not count because it's data directly to srep via stdio.
Srep will have to deploy 8GB virtual temp, depending on how much did it want in the first place, I've seen it needing 10GB, so it's 10GB - 2GB ram restriction (normally srep is set to use 512mb physical memory)
From that 8GB, srep will actually have to seek and do that stuff to grab the repetitions it found and place them where they are supposed to be.
That's 8GB that's being written to disk so far by srep creating it's virtual memory.
srep will have to read a couple of times from that 8GB, it order for it to make writes for 88gb worth of data which are just thousands if not a million of temp files

Reads = 18gb + some reads that srep does to be able to restore 88gb * 0.8
Writes = 8gb + 88gb

raw2hif is run from that 88gb, and 88gb is read to restore the data back to 44gb if ratio was 200% for inflation which is the case.

rawrest also needs to be run 44gb to 44gb just to restore data back to its correct order

reads = 18gb + some reads that srep does to be able to restore 88gb * 0.8 + 88gb + 44gb
writes = 8gb + 88gb + 44gb

total IO = 290gb + some reads that srep does to be able to restore (88gb * 0.8) which is roughly 300gb-350gb in 4 hour of total IO + millions of temp files + lzma reading data from archive + srep reading from VM and giving data to FA while FA is writing to disk, nah, "that's not much work".

Since you said "just the same as with browsing" it's either 350gb total IO is easily written to disk in 4 hours while being bottlenecked by hardware or the hard disk is overworking just to make the archive unpack in 4 hours and overworking means more heat.

BTW, this is just my opinion, some stuff might be incorrect.

Edit:
From that, game takes its own time to load stuff and etc, you complain online then people tell you to defrag, from all that last activity of installing repack, game is like 65GB, you go ahead and defrag, since read and write was interrupted many times because of those million temps, run defrag, windows rearranges data, more IO. 350gb + 65gb x 110-200%. Theoretically, somewhere 450-500gb total IO in 4-24 hours, if you are going to defrag drive straight away after installing.