What IDE do you use?
If you develop an iOS Apps, you use Xcode. If you develop an Android Apps, you use Android Studio. If you develop a windows desktop apps, you use Visual Studio.
I often use AppCode to develop iOS Apps and macOS Apps.
AppCode is a one of an IntelliJ Based IDE, it is used to develop iOS / macOS Apps. Android Studio is also IntelliJ Based IDE. I think they are like a brother or sister.
Change Memory Settings of IDE
The IntelliJ Based IDE such as AppCode and Android Studio can change the memory settings by same way.
I feel a code editor running very slow when the project is very large. If you change memory settings of IDE to assign more memory, the performance of code editor may be improved.
You can change it by follow steps below. Open the large project. The largest project in your work is better.  Open the large source file and build.  Choose “Change Memory Settings” in “Help” menu.
How many MB should you enter?
The IDE will tell you a maximum heap size you should enter. The recommended size is entered default when you open the dialog.
For example, in above screen capture, the meaning of values are below.
Recommended Value: The default value of Maximum Heap Size field. In above screen capture, value is 1920 MB.
Current Value: In above screen capture, 1280 MB.
You can use the default value. If you feel the editor is slow, you can assign more value.
With my working project, the default value is 8192 MB, but I feel slow with this value. I change the maximum heap size to 10240 MB.