Firstly, the last version you can use with WIndowx XP is v3.0.35. You can download it from https://sambapos.org/en/downloads.
Your slow report issue is related to using CE database. I have never used V2 but I think it supports SQL Server as database. If it doesn’t you can upgrade to V3 which does support SQL Server. That should resolve the speed issue. I think SQL Server 2014 won’t work on XP as well, probably need to use 2008 or 2005 edition. However you can read guide to installing SQL Server here (which is for V4 / V5 but at least gives you an idea of the steps involved):
You won’t be able to get much support on this forum for V3, so you are best to upgrade to V4 or V5.
But you should be able to find more info about using SQL Server with V2 or V3 on the V3 site Welcome to SambaPOS V3 Project! | SambaPOS V3 and forum https://forum2.sambapos.org/.
So if you can upgrade from XP to Windows 7 (which you really should - XP is no longer supported by Microsoft so you don’t get any security updates, etc.), then you can upgrade to V4 or V5.
To upgrade V2 to V4:
First upgrade to V3.0.35, download from https://sambapos.org/en/downloads.
Then download the last V4 release from https://sambapos.com/download-sambapos/ and upgrade to V4.
To upgrade V2 to V5:
Follow steps above and upgrade to V4, then upgrade from V4 to V5. There are some tutorials on the forum for upgrading if you need extra help.