Not worth it. Learn to spin. A 48t is only 9% bigger than a 44t, so you need to cycle 9% faster to get the same speed. The power output will be the same, just a different energy source fueling the bike (aerobic v. anaerobic). With time you will as fast as you were with a 48t, but now with higher rpms should be able to hold that speed longer.

What is your smallest rear cog? Unless you can hold 90rpm with your highest gear combo then it is w/o question not worth it.

I thought the same thing some time back. I had a hybrid with the highest gear combo of 48x12. I switched out the 12 for an 11 to be 'faster'. Many miles later I am riding a fixed gear at 48x16 and am much faster than I was on my hybrid because I spin at 90rpm at top speed instead of 60rpm on my top hybrid gear.

A good test? Ride with your 44txsmallest cog for 10 miles and time yourself. The next day ride with your 44txsecond to smallest cog for 10 miles and time yourself. You might surprise yourself.