Delayed response using phone app

I'm getting an odd, delayed performance from my phone. Here are the symptoms:

• When I open the phone app & click on the keyboard there is a delay before it opens.
• When I start dialing a number the keyboard fails to register my taps or clicks for a couple of seconds (I tap & nothing happens), then "catches up" by rapidly beeping & displaying the numbers I had just tapped.
• When the phone rings & I answer, then immediately tap on "Speaker" it fails to switch to speaker immediately. I have to click sometimes 3 times to get the phone on speaker.

Could it be that I have too many names/numbers in my Contacts? I'm a Realtor & do, indeed have hundreds & hundreds. If that could be the cause, what might be the fix? I hope you don't tell me to start deleting contacts, because one at a time would take me eons to make a dent!