Is thicker better when it comes to transmission fluid?

Did you make all of that up, because none of it is true.  Go online and educate yourself on how hydraulic fluids work.  That should take about 14 minutes.  Then come back and ask a question.

I assume you are asking about an automatic transmission. With a thicker fluid the torque converter  would have less less power loss and thereby improve the acceleration. As for speed, modern automatic transmissions have a locking feature that eliminates the slippage in the torque converter at the top gear so a thicker fluid will have no effect on the speed. The thicker fluid will slow down the switching of gears so your acceleration based on proper gear selection will be hampered. 

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If you want more acceleration or speed you need to modify the engine or change the transmission to a manual.

Transmission fluid is a hydraulic fluid not just lubrication. Heavier weight fluid will cause a delay in shifting between gears. Transmissions are designed for compatibility with a certain weight and type of fluid. The fluid is not petroleum based fluid. it is an excellent lube for locks because it doesn't freeze above -40.

don't mess with the fluid in your car.

each transmission is designed to use a specific fluid with a specific viscosity. Use that fluid, which is listed by the manufacturer, or your warranty is void.

The recommended viscosity is what's required. Synthetic being the best. Any deviation risks transmission problems.