In my opinion, it does not make sense to compare XML and JSON parsing times. Choosing one format over the other depends on your use case.

If you only want to store primitive types as supported by JSON in a simple, human-readable format, JSON is the way to go. If you need all the power and complexity of a markup language, use XML. You probably don't want to invent a document format based on JSON.

The bottleneck with parsing JSON and XML usually is not the parsing itself, but the interpretation/representation of the data. An event-based XML parser usually is very fast, but building a complex DOM tree of thousands of small objects is not. If you need to parse XML to nested native data structures such as lists and dictionaries, the slow part will be the interpretation of the parsing results, not the actual string analysis. Since JSON parses right to those primitive types rather than a complex object tree, it will likely be faster.

xmltodict (full disclosure: I wrote it) can help you convert your XML to a dict+list+string structure, following this "standard". It is Expat-based, so it's very fast and doesn't need to load the whole XML tree in memory.

Once you have that data structure, you can serialize it to JSON:

import xmltodict, json

o = xmltodict.parse('<e> <a>text</a> <a>text</a> </e>')
json.dumps(o) # '{"e": {"a": ["text", "text"]}}'