On what factors does speed of mysql depends

[abhishek jain]

Dear Friends,
I have a database with approximately 10 tables with about 1 lakh records
each in 3 tables, I need to know that on what factors does the speed of
mysql depends,
1)Does a table having records effects the speed of data fetch of another
table in the same database.
2)Whats the approximate size of a table ideal for mysql,

Any other factors you want mine attention to be foccused on.
Thanks,
Abhishek Jain