I'm running Sierra. This problem just started, out of the blue a couple of days ago. I'm able to print normally in Chrome and Safari but not with Opera which I've been using several months as my default browser, and have been very pleased with it. It doesn't seem to be a problem with my printer (an HP OfficeJet Pro 8600) as run test pages and print Google sheets perfectly from other browsers. I'm able to print websites and other documents normally in Opera, just not Google Sheets (and occasionally Docs). When I hit Print it does get me to the normal Printer Settings box. But as soon as I hit 'Print' from there it just goes straight to the download file as a .pdf

Sorry for delay, have been w/o service. In answer to bordonidev I'm no longer using Chrome, only Opera v. 39.0.2256.48. To 'arepocam' I have 9 Opera Helper running now. They're consuming probably less than 2% CPU. But under the Memory Tab those 9 Opera Helpers are probably consuming 5 or 6 times the amount of memory than the next 2 highest combined, Opera and DropBox. On the other hand, since the day when I initiated the post where my Opera was running more slowly, that had been going on for a couple of days. Since then including now, the system is running quite well and satisfactorily fast. So perhaps something else was going on back then. I have started shutting down Opera every night, and my Mac every 2 or 3 nights; perhaps that's helping too. Thanks to you both for coming to my aid.

(I just posted this, without realizing it, in the Windows Discussion, so am simply re-posted under Mac, Sorry)

Running El Capitan, v. 10.11.5, with 8GB RAM. Until a few months ago was running Chrome as my default browser and then it really started to slow down terribly, with a lot of ‘Chrome Helper’ consuming resources. I was planning to switch to Firefox until I stumbled upon Opera. My lucky day I guess as I really like it a lot. At first it even seemed to be faster. But now it’s slowing down a lot, and I see many lines of ‘Opera Helper’ in Activity Monitor. It seems that Opera Helper appears as much as nearly 1/2 of everything else combined but perhaps I’m exaggerating a tad. Hopefully someone out there can tell me how to remedy this.

Running El Capitan, v. 10.11.5, with 8GB RAM. Until a few months ago was running Chrome as my default browser and then it really started to slow down terribly, with a lot of ‘Chrome Helper’ consuming resources. I was planning to switch to Firefox until I stumbled upon Opera. My lucky day I guess as I really like it a lot. At first it even seemed to be faster. But now it’s slowing down a lot, and I see many lines of ‘Opera Helper’ in Activity Monitor. It seems that Opera Helper appears as much as nearly 1/2 of everything else combined but perhaps I’m exaggerating a tad. Hopefully someone out there can tell me how to remedy this.