The measured performance impact from the Telegraf / Jolokia agent is very low, and for lowest possible performance impact we advise that you install the data collector on a dedicated host.
There are three parameters that can have a performance impact on the vm / container hosting the Atoms:
Number of JMX metrics the agent is reading
Sampling interval of the agent
Type of JMX metrics the agent read from the Atoms
Bullet 1 and 3 is more or less locked down from Eyer and what we support in the current version (can change with versions). But number 2 is possible to tune within certain limits by the customer (see Adjust the Telegraf sampling interval )