Just found this script on Github to perform a DNS performance test and was running this on my Pi-Hole.
See below the speed results in milliseconds: (Location: Sweden / Stockholm)

DNS Server	Test	Test	Test	Test	Test	Test	Test	Test	Test	Test	Average
Cloudflare	1	1	1	1	2	1	1	1	1	1	1.10
Google	2	1	1	1	22	48	2	12	2	12	10.50
Aduard	22	22	21	21	22	21	21	21	21	21	21.20
Neustar	26	26	26	27	26	26	26	26	26	26	26.10
Norton	26	26	26	27	26	26	26	26	26	26	26.10
Freenom	27	27	27	27	27	27	27	27	27	27	27.00
Clearbrows.	33	41	33	32	32	33	33	33	32	33	33.50
Quad9	33	34	33	33	40	34	34	44	34	37	35.60
OpenDNS	34	34	34	45	35	34	34	45	34	34	36.30
Yandex	31	66	31	31	40	61	31	31	31	31	38.40
Comodo	40	40	40	40	41	53	43	40	40	49	42.60

 

I used a couple of weeks Quad9 which was working fine. Starting from now on to go over to CloudFlare DNS to compare.