Determining whether ArangoDB is faster than MongoDB can depend on various factors, including the specific use case, workload characteristics, dataset size, hardware configuration, and optimization techniques employed. Both ArangoDB and MongoDB are popular NoSQL databases with different strengths and trade-offs, so it's essential to evaluate them based on your particular requirements.

Here are some factors to consider when comparing the performance of ArangoDB and MongoDB :

Data Model : ArangoDB offers a multi-model approach, supporting document, graph, and key-value data models within a single database engine. This can provide advantages for applications that require diverse data structures or relationships between data types. MongoDB, on the other hand, primarily focuses on the document data model.

Query Language and Optimization : ArangoDB's AQL (ArangoDB Query Language) is optimized for multi-model queries and supports complex operations, including graph traversals, joins, and full-text search. MongoDB uses the MongoDB Query Language (MQL), which is tailored for document-oriented queries. Performance can vary depending on the complexity and optimization of the queries.

Indexing and Query Performance : Both ArangoDB and MongoDB support indexing to optimize query performance. The efficiency of query execution can depend on the indexing strategy, query patterns, and dataset characteristics. MongoDB's WiredTiger storage engine offers advanced indexing capabilities, while ArangoDB's RocksDB storage engine provides efficient indexing for document and key-value collections.
Scalability and Replication : Both databases support horizontal scalability and replication for distributing data across multiple nodes. MongoDB's sharding architecture and ArangoDB's SmartGraphs (for graph data) can help improve scalability and performance for large datasets and high-throughput workloads.

Community and Ecosystem : MongoDB has a large and active community with extensive documentation, libraries, and tools available for developers. ArangoDB also has a growing community and ecosystem, although it may not be as extensive as MongoDB's.

Ultimately, the performance comparison between ArangoDB and MongoDB is subjective and depends on your specific requirements and workload characteristics. It's recommended to conduct thorough performance testing and benchmarking in a representative environment to evaluate which database better suits your needs. Additionally, consider factors such as ease of development, deployment, maintenance, and support when making your decision.