I have found that my computer, laptop, tablet and modem need dusting out every once in a while otherwise everything slows down to a crawl. Some virus protectors too will slow things down for me. maybe checking to see whether these will apply and need work will speed things up for you...

also many cable and phone companies, internet providers have a range of "tiers"....how fast the internet is, is based on which internet provider package you have with that internet provider....

example here in NY we have cable, phone and cell phone providers that also provide internet services. they have many packages for me to choose from. when I chose an economical one for my budget I found things to be very slow, when I upgraded a few tiers (paid for a larger, faster internet package) things went back to normal.

Also things like desktop cleaning/defragmenting/ and cleaning cookies, history...can also speed things up for me when I find things have slowed down, lagging.