Website performance can be influenced by numerous factors. If your webpage is loading slowly and you're using AWS Lambda and RDS, here are some steps and optimizations, structured in order of priority, that you can consider:

1. Database Optimization:

Database Queries:

• Optimize any slow-running SQL queries.
• Ensure indexes are applied to columns that are frequently searched, filtered, or joined on.
• Use tools like Amazon RDS Performance Insights to identify performance bottlenecks.

Connection Overhead:

• Use connection pooling if possible.
• Ensure the Lambda function is in the same region and VPC as the RDS instance to reduce latency.

Scaling:

• Scale the RDS instance vertically (choose a larger instance type) or horizontally (read replicas for read-heavy operations).

2. Lambda Optimization:

Memory and Execution Time:

• Increase the memory allocated to the Lambda function. AWS Lambda allocates CPU power linearly in proportion to the amount of memory configured.
• Monitor the AWS Lambda execution time to see if the function is getting close to its timeout.

Cold Starts:

• Cold starts can be an issue, particularly with VPC-connected Lambdas. Consider keeping your Lambda functions warm by using plugins or periodically pinging them.
• If using VPC, ensure that the ENIs (Elastic Network Interfaces) creation is not the bottleneck.

Dependencies and Bootstrapping:

• Minimize the number of libraries and dependencies in your code. If some libraries are not needed immediately, consider lazy-loading them.
• Optimize the bootstrapping process of the application.

3. Content Delivery and Frontend Performance:

CDN:

• Use Amazon CloudFront or another CDN to cache and deliver your content closer to the end-users.

Web Asset Optimization:

• Compress and optimize images, CSS, and JavaScript.
• Use modern image formats like WebP for better compression.
• Minimize the number of requests by bundling CSS and JavaScript.

Caching:

• Implement browser caching for static assets.
• Use cache headers to instruct browsers how long to cache resources.

4. Architectural Considerations:

Serverless Frameworks:

• Consider using a serverless framework like AWS SAM or the Serverless Framework which can provide best practices and optimizations out of the box.

API Gateway:

• If you're using API Gateway with Lambda, ensure the configurations (like caching) are optimized.

Third-Party Services:

• Check if there are third-party integrations on the webpage causing the slowdown. Often analytics scripts, third-party plugins, or widgets can contribute to slow load times.

5. Monitoring and Analysis:

Logging and Monitoring:

• Ensure logging is set up properly in AWS Lambda and use tools like Amazon CloudWatch to monitor performance metrics.
• Set up alarms for slow-running Lambda functions or RDS queries.

Web Performance Tools:

• Use tools like Google PageSpeed Insights, GTmetrix, or WebPageTest to analyze website performance and get specific recommendations.

Remember, this is a structured list based on general knowledge and your provided information. The actual bottlenecks might vary, so it's crucial to monitor and diagnose the specific components of your infrastructure to identify the root causes.

You may want to activate AWS X-Ray to help troubleshoot these issues. Also, check out Using Lambda Insights. Another tool, AWS Lambda Power Tuning.