@ OP. Lighter and more aero components will probably net you an extra 0.1 to 0.3mph. A world class cyclist can put out about 0.5 continuous horsepower (~400W). Some of us are good for 0.3 continuous horsepower on a great day. Dropping a few lbs isn't going to make a huge difference in power to weight ratio. A cyclist worst enemies are head wind and hill. You have no control over these variables, so you need to ride smart. Position the saddle and stem so that you'll be comfortable way down on the drop, and up to 45 degree lean angle. This will allow you to ride in many positions to give various muscle groups a break. Less fatigue will allow you to output more power at the crank.
Rise smoothly. Don't rock the bike when you climb. Try to apply power throughout the whole pedal stroke, not just on the down-stroke. Keep the crank rpm north of 60, especially on a climb. Switch to a lower gear if needed to maintain the rpm to deliver the power to the road. A skinny 23C at high pressure can cause your bike to bounce on the road, reducing traction needed to propel the bike. I prefer 28 or 32 for city riding.
Get a speedometer. Go out on a calm day and record your average speed. Practice proper riding technique. Note the change in speed. It can take months to add 2mph to your cruising speed.