Grokking the System Design Interview
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Latency vs Throughput

Latency and throughput are two critical performance metrics in software systems, but they measure different aspects of the system's performance.


  • Definition: Latency is the time it takes for a piece of data to travel from its source to its destination. In other words, it's the delay between the initiation of a request and the receipt of the response.
  • Characteristics:
    • Measured in units of time (milliseconds, seconds).
    • Lower latency indicates a more responsive system.
  • Impact: Latency is particularly important in scenarios where real-time or near-real-time interaction or data transfer is crucial, such as in online gaming, video conferencing, or high-frequency trading.
  • Example: If you click a link on a website, the latency would be the time it takes from the moment you click the link to when the page starts loading.


  • Definition: Throughput refers to the amount of data transferred over a network or processed by a system in a given amount of time. It's a measure of how much work or data processing is completed over a specific period.
  • Characteristics:
    • Measured in units of data per time (e.g., Mbps - Megabits per second).
    • Higher throughput indicates a higher data processing capacity.
  • Impact: Throughput is a critical measure in systems where the volume of data processing is significant, such as in data backup systems, bulk data processing, or video streaming services.
  • Example: In a video streaming service, throughput would be the rate at which video data is transferred from the server to your device.

Latency vs Throughput - Key Differences

  • Focus: Latency is about the delay or time, focusing on speed. Throughput is about the volume of work or data, focusing on capacity.
  • Influence on User Experience: High latency can lead to a sluggish user experience, while low throughput can result in slow data transfer rates, affecting the efficiency of data-intensive operations.
  • Trade-offs: In some systems, improving throughput may increase latency, and vice versa. For instance, sending data in larger batches may improve throughput but could also result in higher latency.

Improving latency and throughput often involves different strategies, as optimizing for one can sometimes impact the other. However, there are several techniques that can enhance both metrics:

How to Improve Latency

  1. Optimize Network Routes: Use Content Delivery Networks (CDNs) to serve content from locations geographically closer to the user. This reduces the distance data must travel, decreasing latency.
  2. Upgrade Hardware: Faster processors, more memory, and quicker storage (like SSDs) can reduce processing time.
  3. Use Faster Communication Protocols: Protocols like HTTP/2 can reduce latency through features like multiplexing and header compression.
  4. Database Optimization: Use indexing, optimized queries, and in-memory databases to reduce data access and processing time.
  5. Load Balancing: Distribute incoming requests efficiently among servers to prevent any single server from becoming a bottleneck.
  6. Code Optimization: Optimize algorithms and remove unnecessary computations to speed up execution.
  7. Minimize External Calls: Reduce the number of API calls or external dependencies in your application.

How to Improve Throughput

  1. Scale Horizontally: Add more servers to handle increased load. This is often more effective than vertical scaling (upgrading the capacity of a single server).
  2. Implement Caching: Cache frequently accessed data in memory to reduce the need for repeated data processing.
  3. Parallel Processing: Use parallel computing techniques where tasks are divided and processed simultaneously.
  4. Batch Processing: For non-real-time data, processing in batches can be more efficient than processing each item individually.
  5. Optimize Database Performance: Ensure efficient data storage and retrieval. This may include techniques like partitioning and sharding.
  6. Asynchronous Processing: Use asynchronous processes for tasks that don’t need to be completed immediately.
  7. Network Bandwidth: Increase the network bandwidth to accommodate higher data transfer rates.


Low latency is crucial for applications requiring fast response times, while high throughput is vital for systems dealing with large volumes of data.

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