We can check record page performance in lightning for Phone and Desktop.
To check the performance of lightning page, please follow below steps:-
1. Go to Lightning App Builder
2. Click on the record page and edit it.
3. Click on Analyze button as shown below.
4. We will get page performance result as shown below.
Analysis of page performance on phone is only available on pages whose template supports the phone form factor.
Refer below link for more info.
https://help.salesforce.com/articleView?id=lightning_page_performance.htm&type=5