What should i prefer for better transaction speed and data fetching?
Deploy contracts on my own node or use infura?
Plz let me know.

Your own node is always faster, I'd imagine

I guess it depends on your requirements also. Transaction speed depends on your connectivity also

Is it good to use infura for the long term usage?

Depends on your needs. I wouldn't use it for any serious production project but it's handy for testing and prototyping

Yup I'm using it for testing that's why I asked here, because i have to deploy it on Mainnet very soon.

Well most likely it works just fine also for production releases. It's just a matter of do you want to trust yourself for running a node or trust a third party for doing it for you

Yup that's true, thanks for your help mate :-)