Ssd, more ram(make sure your os is 64bit), overclocking cpu, running an antivirus to make sure you don't have viruses, make sure you don't have alot of things that start automatically if your start times are long.
Cleanup and defrag your hard drive, uninstall any unnecessary software, limit your start up items. Then run several different virus scans to make sure you don't have malware. There are a series of videos on Youtube that show how to change certain settings that can make difference as well. The biggest thing for you that would help is to increase your RAM to 8 GB and move your Windows to an SSD. This alone would make it seem like a whole new computer.
I revived an old Toshiba laptop (Pentium T4500 CPU) with an SSD. Now takes like 10-15 seconds to boot Windows 10.
A RAM upgrade to 6 or 8 GB would be the next step after the SSD.