Question

Does UserControls in asp.net degrades performance.

MasterPage has its own life cycle
Page has its own life cycle and
UserControls has its own life cycle.

UserControls helps to divide work load and are easily maintainable, but does UserControls down grades performance of asp.net application?

Answer 1

I’ve never seen them decrease performance, unless you do something foolish like have each user control be responsible for it’s own DB look-up, and then bind them in a Repeater or something like that. If you use common sense, they should not degrade performance noticeably.

If you’re talking optimizing down to the processor cycle, however, I would guess they would not because of how everything gets compiled down to MSIL, and then to Machine code, so I would guess the compiler can sort it out and would treat a user control no differently than if you had all the constituent controls directly on the page.
Edit – added

This article argues for how they can actually improve performance. Interesting.

In addition to their reusability and
flexibility, Web user controls can
take advantage of the ASP.NET caching
engine to implement what is referred
to as “fragment caching.” Essentially,
fragment caching allows a Web
developer to control the HTML caching
of individual controls on a page,
including setting the duration and
caching various versions of the
control based on query string, control
properties, browser type, and even
custom strings. The ability to cache
only portions of pages is powerful
since a portion of a page will often
access relatively static data stored
in a relational database or accessed
through an XML Web service, while
other portions of the same page
manipulate dynamic data. For these
static portions, creating a Web user
control and setting caching options
greatly reduces the number of database
round trips, thereby increasing
performance. In most instances, using
ASP.NET caching judiciously is the
single biggest performance improvement
that can be made.

Good question. Again, I learned something new. Thank you.