An alert message is displayed in the form of "application name not optimized...." in macOS High Sierra 10.13.4. and later
Details are shown below.
PHENOMENON
An alert message is displayed when a 32-bit application is launched. This message appears only once when the application is initially launched,
Even when the application is launched in the background, this warning message appears only initially.
Support page of Apple
https://support.apple.com/en-us/HT208436
HANDLING
Click OK, and close the message. There is no problem with the subsequent operation.