Why are nested weights bad for performance? Alternatives?

Nested weights are bad for performance because:

Layout weights require a widget to be measured twice. When a LinearLayout with non-zero weights is nested inside another LinearLayout with non-zero weights, then the number of measurements increase exponentially.

It's better to use RelativeLayouts and adjust your view according to the places of other views without using specific dpi values.

Update: As we know the percent support library is deprecated from API level 26. ConstraintLayout is the new way to achieve the same flat xml structure.

Updated Github Project

Updated Samples:

<android.support.constraint.ConstraintLayout     xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:id="@+id/fifty_thirty"        android:layout_width="0dp"        android:layout_height="0dp"        android:background="#ffff8800"        android:gravity="center"        android:text="@string/fifty_fifty_text"        android:textColor="@android:color/white"        app:layout_constraintHeight_default="percent"        app:layout_constraintHeight_percent="0.5"        android:textSize="25sp"        app:layout_constraintTop_toTopOf="parent"        app:layout_constraintWidth_default="percent"        app:layout_constraintWidth_percent="0.5" />    <TextView        android:layout_width="0dp"        android:layout_height="0dp"        android:background="#ffff5566"        android:gravity="center"        android:text="@string/fifty_fifty_text"        android:textColor="@android:color/white"        android:textSize="25sp"        app:layout_constraintHeight_default="percent"        app:layout_constraintHeight_percent="0.5"        app:layout_constraintLeft_toRightOf="@id/fifty_thirty"        app:layout_constraintTop_toBottomOf="@id/fifty_thirty"        app:layout_constraintWidth_default="percent"        app:layout_constraintWidth_percent="0.5" /></android.support.constraint.ConstraintLayout>

Update: Great news android percent support library solves our problem of performance and nested messy weighted LinearLayout

compile 'com.android.support:percent:23.0.0'

Demo HERE

Consider this simple layout to demonstrate the same.

<android.support.percent.PercentRelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:id="@+id/fifty_huntv"        android:layout_width="0dp"        android:layout_height="0dp"        android:background="#ff7acfff"        android:text="20% - 50%"        android:textColor="@android:color/white"        app:layout_heightPercent="20%"        app:layout_widthPercent="50%" />    <TextView        android:layout_width="0dp"        android:layout_height="0dp"        android:layout_toRightOf="@id/fifty_huntv"        android:background="#ffff5566"        android:text="80%-50%"        app:layout_heightPercent="80%"        app:layout_widthPercent="50%"        /></android.support.percent.PercentRelativeLayout>

Avoided performance degrader nested LinearLayout with weights.Really awesome!!!.

I think (and I will probably be flamed for this), but again I think my phone has a quad core processor to rival (if not utterly destroy) most peoples home PC's.

I also think this kind of hardware capability is the future of phones.

So I come to a conclusion, that as long as you are not getting carried away with nesting (in MHO a layout should never be more then 4 levels deep, and if it is you are probably doing it wrong), your phone could care less about having weights.

There are many things you can do that will have a much more far reaching effect on performance, then worrying about your processor doing some extra math.

(please note that I am being slightly humorous, and so not to take anything too seriously from this post, other then the idea that there are other things you should optimize first, and that worrying about a 2-3 level deep weight is not helping your health)