doc: added partial rendering description

README.md

@@ -60,6 +60,15 @@ The task scheduler has been meticulously crafted to conceal complexity, streamli
 <p align="center">
   <img width="900" height="auto" src="https://github.com/thorvg/thorvg/blob/main/res/example_thread.png">
 </p>
+<br />
+ThorVG supports smart partial rendering, enabling more efficient rendering workflows by updating only the portions of a vector scene that have changed. By internally tracking modified regions, it minimizes unnecessary redraws and optimizes overall performance. This feature delivers significant performance benefits, especially in animations and interactive graphics where only part of the scene changes between frames. By avoiding full-scene rendering, it can reduce computational workload—making it particularly well-suited for mobile and embedded systems where energy efficiency is essential. It also help to ensure smoother visual updates, especially for dynamic UIs and real-time animations, where rendering responsiveness is critical.<br/>
+<br/>
+<p align="center">
+  <img width="900" height="auto" src="https://github.com/thorvg/thorvg/blob/main/res/example_partial.png">
+</p>
+<br/>
+The figure above illustrates how ThorVG detects geometry changes and calculates the minimal redraw region (highlighted by the red box) that needs to be updated. Only the modified area between the previous and current frames is selectively redrawn, significantly enhancing performance.<br/>
+<br />
 Today, ThorVG provides its own implementation of multiple raster engines, allowing you to choose the one that best suits your app and system preferences.<br/>
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