Skills performance guidelines
General performance tips
Load resources at start up
If you need to retrieve data that the user may request (for example, a list of songs, images, locations), load it at startup, not after the user requests the information.
Avoid large images
Use images that are 720 pixels wide or less. Also consider compressing images to reduce their file size.
Avoid long texts
Keep speech text short. As you would expect, it takes longer to process long strings. It's better to split long messages into several shorter ones if possible. Also, the amount of time it takes to process speech depends on whether you use text strings, SSML, MP3 playback, etc. You may want to experiment with different methods.
Avoid long running processes
Identify the parts of your skill that require the most processing time, and investigate how you can make these parts faster.
If your skill repeatedly loads the same data to perform lookups, consider caching the data. Is there any other data that you can also cache in memory?
If your skill calls an external service, determine whether there's a latency issue. Can you accomplish the same task using local code in your skill? Can your skill work without this service?
Azure performance guidelines
Same region deployment
Deploy all your services in the same Azure region. This includes your bot, LUIS, and any external services that your bot uses.
If you are using LUIS for language understanding, create a key in the same Azure region that your bot runs in. If you created your LUIS service in a different region, you should move it to the same region as your bot.
Avoid cold starts in Azure
If an Azure function or Web app is not used for a period of time (typically about 20 minutes), Azure recycles it. Recycled functions and apps can take up to 10 seconds to restart. This is known as a cold start. You can prevent cold starts by enabling the Always On option in the application settings of your Azure Function or Web app.
Azure functions and Web apps that are on Free or Shared App service plans do not have the option to be always on.
Disable ARR affinity cache
If you are not using Azure's automatic scaling feature, you should disable application request routing (ARR). For more information, see Disabling ARR’s Instance Affinity in Windows Azure Web Sites
Additional performance resources