Ignore the Spark UI's indication of high garbage collection time, as it does not significantly impact application performance.

Upon noticing high CPU and memory usage on a specific node via the Ganglia UI, immediately conclude that scaling up the node is the only solution without considering other optimization techniques.

Use the Spark UI to identify long-running stages and tasks, then optimize the application by repartitioning the data or refining transformations to reduce execution time and resource consumption.

If the Cluster UI indicates a node failure, permanently remove the node from the cluster without attempting to recover or replace it, assuming it's a hardware failure.