Great questions, thanks.<p>&gt; <i>We started using ui-router recently and from quick profiling of rendering it looks like a lot of time is spent in ui-router transitions (chained promises)</i><p>I&#x27;ve never profiled transitions specifically, but the number of promises is generally determined by (a) how many templates you have in a target state, and (b) how much asynchronous data (resolves) each state loads.<p>&gt; <i>and in generating&#x2F;validating ui-sref links.</i><p>State names themselves are validated once on initial template load. If the target is parameterized, we do set up a $watch() on the parameter values to update the href, which is a small incremental perf hit per use (and you&#x27;ll naturally tend to get more churn the more deeply-nested the scope in which you use them is).<p>&gt; <i>Do you have any pointers to differences between Component Router and ui-router? I&#x27;m especially interested in pitfalls of both.</i><p>The biggest differences that I&#x27;m aware of are:<p>- Component Router supports components (naturally), which UI Router does not (this is on the roadmap)<p>- Component Router&#x27;s transition pipeline appears to be more flexible than UI Router&#x27;s (we&#x27;re refactoring heavily to encapsulate &amp; expose more APIs)<p>- As with ngRoute, Component Router&#x27;s configuration binds view components (or controllers&#x2F;templates in ngRoute&#x27;s case) directly with URLs, whereas UI Router provides a more sophisticated abstraction in the form of a hierarchical state machine, which many people find more ideally-suited to large, complex apps (see other comments)<p>- UI Router provides more sophisticated abstractions for encapsulating and modeling your domain in terms of URLs, for example, Type objects [0]<p>&gt; <i>I haven&#x27;t debugged ui-router much yet, but maybe I&#x27;m doing something wrong</i><p>Let me know if you encounter any specific issues, or post to StackOverflow. One or more of us are usually fielding questions there.<p>[0] <a href="https:&#x2F;&#x2F;angular-ui.github.io&#x2F;ui-router&#x2F;site&#x2F;#&#x2F;api&#x2F;ui.router.util.$urlMatcherFactory#methods_type" rel="nofollow">https:&#x2F;&#x2F;angular-ui.github.io&#x2F;ui-router&#x2F;site&#x2F;#&#x2F;api&#x2F;ui.router....</a>