Performance Consideration For C# Conditional Statements

More data about this analysis is available with the code repository. Unit of measurement is elapsed ticks from the stopwatch. First case true performs approx 6 times faster than the last case true in if- else if condition.

Switch Case

With the switch case also, we will be doing the same test as follows,

Code Sample

More data is available with code repository In Switch case, we can see there is not much difference in their performances on the basis of order. It is almost the same.

Conclusion

With the above study, we can easily conclude the following and use them in our assignment,

Placement order of "true condition" impacts the performance

• As we saw here, we compared the true with the extreme scenario and figured out the impact on performance. Hence try to place the conditions in order of their frequency.
• We see here, if-else if has the biggest performance difference (up to 6-7 times) while Switch case doesn't differ much and it is almost the same with the placement of condition.
• Having "Multiple If conditions" impacts the most as it evaluates all conditions. If-else if doesn't evaluate once it finds the true condition and Switch case evaluates only the true case.

When to use what?

• When we are certain about the frequency and order of condition, use if-else if.
• When we don't know the frequency and it could be random, still if-else if has better performance. See the ticks elapsed in the last condition If-else if vs first condition switch case from the above table.
• Do NOT use multiple If statements, as it will impact the performance as it will evaluate the expression again and again even after true condition is met. Hence we don't see much difference in performance based on order. Similarly, we don't see a performance difference with Switch but if we compare Switch with multiple if, multiple if gets an edge.
• So the preference of C# Conditional Statements goes in this order - #1 - If- Else If -> #2 Multiple If -> #3 Switch case.
• If there are not many conditions and they are straightforward then Switch case can be considered as it provides better readability over either of the If conditions and on a performance front doesn't impose a huge penalty.
• If we need to use Switch case for pattern matching (as we have done in this example) and if there are too many scenarios then dictionary with the query can be a better contestant for this scenario.
• When we have multiple OR expressions in conditional expressions the Switch can be more readable than If-else if. The example used in this article can be re-written and we will analyze the performance as well.

In this way we can see the data and here again if-else if is the clear winner. When the first condition meets true then switch case takes approx 12 times more than If-else if. On the other hand, if Last condition is true then also If- else if has a gain of 1.5 time faster processing.

Disclaimer

For this analysis, I have used an extreme case scenario as in first and last, to show the significant difference in performance and comparison. Your real life scenario may differ but I hope that this article gives you a better understanding of how and what to use from conditional statements in C#.

Share your feedback and download the code to experiment further.