this is still an issue for me

I already have 8 GB RAM and I barely have data in my hard disk, tell me if you have any solution. I know when to upgrade to the new machine. 

If the problem is that the system is slow, see above:  replace the hard drive with a 2.5" SATA SSD and make sure you max out the RAM to 8G.  
Beyond that, you can't expect miracle performance from a 10 year old notebook.  It may be time for a new system.

Replace the hard drive with a native SSD.  That's the single best (and really the only) way to boost performance on this system.

This is still not resolved for me 

If you haven't replaced the hard drive with an SSD, nothing is going to improve short of buying a new system.

Welcome to the Dell Community @Ajay Apur 

Here are a few things you can try to increase system performance!!!

1. In “System Properties” set  Performance to  “Adjust for Best Performance”
2. Then adjust “Virtual Memory” as needed.  “More is better but it uses Hard Drive space”
3. Reboot.
4. Do a “Disk Cleanup”
5. Then a “Disk Defragmentation” (Skip if SSD is installed)
6. Open an Administrative Command Prompt and Run chkdsk c:/f    “Yes to run after reboot”
7. Reboot.

Best regards,

U2