first, thank you for sharing LOINC as FHIR resources.
my feedback/information for other dev after few tests :
it will be great to make available a service to retrieve data for more than one loinc code inside a fhir bundle.
i tried to parse the answer from the https://fhir.loinc.org/CodeSystem/$lookup?system=http://loinc.org&code=XXXXXX call , with the Parameters JAVA resource from HAPI FHIR but most of data were not available cause of value[x] type . could not find solution with this … so i create a specific small json parser and could retreive all LOINC codes in 135 minutes …
i used a scala akka actors (i’m newbee with that tech) and could not made quicker treatment .
around 1000 calls -> 1m30s
point 2 is critical as the FHIR goal is to have a standard with data exchange .but maybe a HAPI FHIR limit (or my limit in HAPI FHIR understanding.