You used to be able to Preload paclet data

PacletName["All", "Preload"]

For e.g. for chemical data you'd type:

ChemicalData["All", "Preload"]

See also this support article

I've heard rumors (but haven't tried it myself) that in v10 this doesn't work anymore.

You used to be able to Preload paclet data

PacletName["All", "Preload"]

For e.g. chemical data you'd type:

ChemicalData["All", "Preload"]

See also this support article

I've heard rumors (but haven't tried it myself) that in v10 this doesn't work anymore.