9. A method comprising: sending, over a network, from a server system, to a first source, one or more requests to determine a latency or speed associated with the first source; receiving, from the first source, at the server system, one or more replies to the one or more requests; determining, by the server system, based on the one or more replies, the latency or speed associated with the first source; receiving, from a client, at the server system that is operated by a first party, a first client request for first data; in response to receiving the first client request, generating a plurality of requests, each of which requests a different set of data from the first source that is (1) remote relative to the server system and (2) is operated by a second party that is different than the first party; wherein generating the plurality of requests comprises, based on the latency or speed, determining, by the server system, a size of multiple requests of the plurality of requests that are sent to the first source; sending the plurality of requests over the network from the server system to the first source; after sending the plurality of requests from the server system to the first source, receiving a plurality of responses from the first source; sending, from the server system, to the client, data from the plurality of responses; wherein the method is performed by one or more computing devices.
9. A method comprising: sending, over a network, from a server system, to a first source, one or more requests to determine a latency or speed associated with the first source; receiving, from the first source, at the server system, one or more replies to the one or more requests; determining, by the server system, based on the one or more replies, the latency or speed associated with the first source; receiving, from a client, at the server system that is operated by a first party, a first client request for first data; in response to receiving the first client request, generating a plurality of requests, each of which requests a different set of data from the first source that is (1) remote relative to the server system and (2) is operated by a second party that is different than the first party; wherein generating the plurality of requests comprises, based on the latency or speed, determining, by the server system, a size of multiple requests of the plurality of requests that are sent to the first source; sending the plurality of requests over the network from the server system to the first source; after sending the plurality of requests from the server system to the first source, receiving a plurality of responses from the first source; sending, from the server system, to the client, data from the plurality of responses; wherein the method is performed by one or more computing devices. 18. One or more non-transitory storage media carrying instructions which, when executed by one or more processors, cause performance of the method recited in claim 9 .