Is there anything that I can download that will make my extremely slow lagging phone run fast and smooth like when it was new?

Hi. Windows updates the drivers automatically once a new digitally signed driver is detected specially Windows 10. By lag do you mean applications open slower than usual or do you mean browsing with a web browser has become slower? If the latter, try clearing your browser's cache.
- On Mozilla Firefox: Press CTRL+SHIFT+DEL simultaneously and click Clear Now
- On Internet Explorer browser: Press CTRL+SHIFT+DEL simultaneously and click Delete
- On Google Chrome: Press CTRL+SHIFT+DEL simultaneously and click Clear Browsing Data
- On Microsoft Edge: Press CTRL+SHIFT+DEL simultaneously and click Clear

Frozen how? You can't open it ? Blackberry can do this sometimes if you drain the battery completely.. you must leave it plugged in until opens. Or, you can try a hard reset doing this:

1. Perform a hard reset to wipe all data from the BlackBerry Classic.
2. Open BlackBerry Link on your computer.
3. Connect the device to your computer using the USB cable.
4. Select your device on the left pane.
5. Go to "Back Up & Restore" > "Factory Reset" (Windows) or "BlackBerry Link" > "Preferences" > "Reload" > "Reload" (Mac OSX).

Download Opera Mini browser. (Red O icon) Your downloads with run smooth and fast with no problem

If its a free download or you already have the sim, then try it, otherwise if you must fork out your hard-earned cash, probably not advisable.
The 'need for speed', or higher CPU clock-speed, is to allow the sound, video frames, rendering and algorithm calculations to all run smoothly in sync.
Check if they specify 'Absolute Minimum Requirement'.
On my old PC, an iNtel P4 1.6GHz single processor running Win XP, 2GB RAM, I barely managed to run intensive resource-hungry games, but often ended up with a frustrating 'slide-show' or total freeze.
After upgrade to 64-bit 3.58GHz core-2-duo, 8GB RAM, i'm thrilled at SMOOTH performance.

it may be you have installed a kind of application that takes a lot of CPU usage of your phone.
try to install a kind of task killer application and kill them all.

If you don't have it, I recomend the Advanced Task Killer App. It force closes any program running in the background making things run more smoothly.

I have a Techniques SL-23--just bought two brand new belts. One runs too slow and the other too fast.

How do I fix it?

it needs to reprogram again.

erase all of memory and caches and re-install fresh file

most cases are fixed in that way.

You normally have 3 screws - idle speed - slow running and fast running.
First take care as if it runs faster than idle speed that chain will be whipping around also.

Second you have to determine what is the problem. Is it faulty at low speeds or high speeds ? or won't it idle.
If it has turn stops fitted to the screws you only have a small adjustments either way.

If it won't idle, try turning in the idle screw a half turn - until the chain just starts to move slowly.
If its dying at slow speeds, get is going and slow turn the slow screw out until it starts to run a bit rough then turn it back in to the point where its running smoothly.

Bad fast speed can be caused by simple things such as a blocked muffler ( insects too - I had one blocked off by a mudnest wasp) - otherwise get it running at full and adjust the fast screw as per the slow one - out till its rough then back in slowly until its smooth.

Suggest before all this tho that you get it running with the cover off the carby and then give it a good squirt of carby cleaner first - it may just clear out any 'poop' thats there.

(Have faith even tho I have a Poulan with a carb that refuses to run on anything but carby cleaner. I have pulled it apart a few times and renewed all the perishable bits buts its a real pig)

What kind of files are you downloading? wap isnt that fast.

also you can perform a wap reset with *2767*927#
You might need to re enter the wap information after that.