Are you searching for the best growth stocks to give your portfolio a refresh in the new year? It's been a crazy 11 months for investors, and the market continues to be full of surprises. Stocks that were pre-pandemic favorites in sectors like travel and retail in 2019 have sunk to all-time lows, while many stocks whose businesses thrive on the stay-at-home regimen continue to ride record highs.

When it comes to picking growth stocks (or any other stock for that matter), it's important to avoid focusing too heavily on fads. Rather, you should fill your portfolio with companies that you fundamentally believe are quality long-term buys and that ideally, you're willing to hold for at least three to five years.

Let's take a look at two of the highest-growth stocks in the market today that are also primed to deliver exceptional shareholder returns for the next decade or longer.

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Image source: Getty Images.

Roku

Streaming services have skyrocketed to new heights of popularity since the pandemic began, establishing a decided shift toward the new future of entertainment. Roku (NASDAQ:ROKU) fills a very specific niche within this industry.

The company makes streaming players and software that enhance the viewer's digital entertainment experience. Roku also operates its own content-streaming platform called The Roku Channel. Through The Roku Channel, users can subscribe to well-known services like HBO Max and Showtime and pay for it all in one bill each month. The Roku Channel also features a wealth of free content, so it offers something for every type of viewer.

Roku's third-quarter revenue shot up 73% compared to the third quarter of 2019, and its platform revenue grew 78% year over year. The company added nearly 3 million new incremental active accounts in the three-month period, while The Roku Channel achieved landmark viewership of roughly 54 million individuals. Roku's players also generate consistent consumer demand, with player unit sales spiking 57% in the third quarter. Roku continues to make meaningful strides to expand its advertising partnerships. Management said that "Q3 was the strongest quarter in the Platform segment's history driven by strong growth in advertising as brands embraced connected TV platforms like Roku, we expanded the reach of The Roku Channel, and saw a significant increase in content distribution activities."

The pandemic may have accelerated demand for digital media and media-streaming technology, but these trends won't diminish once the world returns to normal. Roku's business model and end-to-end platform that provides both the software and hardware needed for the ultimate streaming experience make it a compelling buy in an increasingly digital age.

GrowGeneration

Pot stock GrowGeneration (NASDAQ:GRWG) had a remarkable year in 2020. The hydroponics retailer saw its shares grow from about $4 last January to $40 at the end of December -- a roughly 900% gain. Grow Generation is the nation's largest chain of specialty hydroponic and organic garden centers with 40 retail locations across the U.S.

GrowGeneration also entered the pandemic economy from a place of remarkable strength, having reported 176% revenue growth in 2019. The company hasn't wavered in reporting consistent, record revenue increases throughout the pandemic while continuing to expand its retail presence in new key markets. In the first quarter of 2020, GrowGeneration reported year-over-year revenue growth of 152%, which it followed with 123% revenue growth in the second quarter and 153% revenue growth in the third quarter. Same store sales also surged 58%, 49%, and 73% during these respective quarters. GrowGeneration's online sales likewise soared to record highs during the pandemic, growing 112% year over year in the third quarter alone.

The company released its preliminary financial results for the full year on Jan. 11. According to these early figures, GrowGeneration's 2020 revenue surged 140% year over year, while its fourth-quarter revenue grew 142% from the year-ago period. Management also said that same-store sales were up 58% in the fourth quarter and 63% for the full year, while the company added a whopping 14 new retail locations to its roster of stores during the 12-month period.

CEO Darren Lampert said in the preliminary report:

We delivered strong shareholder value in 2020, with triple-digit revenue growth despite unprecedented challenges and an uncertain environment. This growth came through strategic acquisitions of best-in-class hydroponic stores, exceptional same-store sales growth, and the expansion of our omnichannel and private label offerings -- a strategy we will accelerate this year ... We expect significant revenue growth in the year ahead as we continue to execute on these initiatives.

Management is projecting between $335 million and $350 million in revenue for the full-year 2021. The company also expects to significantly grow its retail presence in 2021 and add 15 new locations before the year is out. 

In an industry that has historically been plagued with volatility, GrowGeneration's exceptional financial performance and stellar growth prospects during the worst recession since the Great Depression make it a shining star in the marijuana universe. If its performance over the past year is any indication, this unstoppable growth stock is just getting started.