300-445 Question 200
Single answerA company has noticed that one of their web applications is experiencing slow load times for end-users. You are tasked with diagnosing the issue using browser waterfall data. Upon examining the waterfall chart, you notice significant delays during the 'Time to First Byte (TTFB)' phase. What is the MOST likely cause of this issue?
- A
High server processing time due to inefficient backend code
- B
Large image files causing excessive download times
- C
Client-side JavaScript execution blocking rendering
- D
Too many HTTP requests for small resources
Show answer and explanation
Correct answer: A
Explanation
The Time to First Byte (TTFB) represents the delay between when a request is sent and the first byte of the response is received. This delay is often caused by server-side inefficiencies, such as poorly optimized backend code, slow database queries, or overloaded servers. By focusing on server-side performance, the root cause of high TTFB delays can often be identified and resolved.
- A. Correct.
High server processing time is a common cause of delays in the Time to First Byte (TTFB) phase, as it indicates the time taken by the server to process the request and start sending data back to the client.
- B. Incorrect.
Large image files contribute to slow load times, but they would primarily impact the 'content download' phase of the waterfall chart, not the TTFB.
- C. Incorrect.
Client-side JavaScript execution blocking rendering would appear later in the waterfall during resource rendering and execution, not in the TTFB phase.
- D. Incorrect.
Too many HTTP requests for small resources would lead to delays seen in the 'resource request' section of the waterfall, not the TTFB.