Why is Gmail search slower than Google search?

Focus on the architectural differences between Gmail and Google Search. Consider how Gmail's search must index and retrieve data from a vast number of user emails, which includes complex filtering and ranking algorithms based on user context and privacy. Discuss the trade-offs between real-time search capabilities and the need for thoroughness in retrieving relevant emails. Additionally, touch on the impact of data size, indexing strategies, and the potential for latency in user-specific queries compared to the more generalized and optimized algorithms used in Google Search.