Have you another XP machine you can use and transfer the file to that one and see what transfer speeds you get?
This issue has kind of plagued me as I use Linux a lot. When I transfer large files from a Linux machine to my Linux NAS's the speed is a generally constant 60~80Mbps (Gigabit LAN, cat6 cabling etc). Windows 10 it drops to around ~11Mbps, if I am lucky, it may hit 25Mbps. I have read up on this and from a windows 10 Forum:
Hi all,
This issue is from when they made windows xp, Microsoft did think lets make a bandwidth reservation, what is a registry setting.
If you have 1Gb network throughput, what is 100% there would be 15% till 20% reserved for Voip, error and other stuff (this is agreed over the whole world).
So if I have large data transfers from my windows 10 computer to my NAS (openmediavault, unix/ Linux, which don't care if I use my hardware full potential) and visa versa, I will get a transfer speed of around the 84MB a 86MB, which is around 84% usage of my 1Gb network (16% is for Voip and stuff).
If I do the same thing between two windows machines is the datatransfer only 30MB max.
Microsoft thought lets reserve 60% of the bandwidth and use only 40%, now if you have 1Gb network (100%) and only use 40% which is to be handled as 100%, minus the 15% till20% reserved for voip and error, you will get 25MB to 30MB datatransfer. then it should be the case that if we have 2 datatransfers from one machine to 2 different machines, the transferrate should be both around the 25MB a 30MB, but this is in best case.
Within windows7 can this problem be resolved, by Disable Bandwidth Limit...
I used for this GPEDIT.msc and then within computer Configuration, Administrative Templates, Network, QoS Packet Scheduler.
Double-click on Limit reservable bandwidth.
And disable it.
IMPORTAND NOTE: this has to be done on all windows machines. and watch out with the use of Gpedit.msc
Windows Forum...
It looks like it is down to a Windows bandwidth management issue....
Don't even get me started on USB3 file transfer on Windows...

I have been programming on computers since the ZX81.
I am an apprentice trained Electronics Engineer with qualifications to back it up.
I have been repairing computers since 1996.
Yet to some people I still know nothing...