Effect of too many columns

Greetings,

Is there any performance penalty of having too many columns in
a table in terms of read and write speeds.

To order to keep operational queries simple (avoid joins) we plan to
add columns in the main customer dimension table.

Adding more columns also means increase in concurrency in the table
as more and more applications will access the same table.

Any ideas if its better to split the table application wise or is it ok?



Regds
mallah.