Removing Integer Overflow Checks
This is conceptually similar to array bounds checking. Whereas the programmer
determines the upper and lower bounds of arrays, the ranges of the basic data
types are set in stone. Whenever you perform any calculations on integer types,
VB automatically checks to make sure that the resulting values can still be stored
in an integer variable. VB will raise an error code if you try to overstuff an
integer variable with a value that it can’t hold.
Just like all the other built-in checks, testing for overflow takes some processing
time. If you don’t want to spend time on these checks, you can turn off
Removing Floating-Point Error Checks
This is similar to integer overflow, but applies to the nonintegral data types
(that is, singles and doubles). VB’s automatic tests also check for division
by zero. If you test your code and are confident that you aren’t performing
any disallowed arithmetic actions, you can save the overhead of these tests by
deactivating them with this optimization.