Why is there a significant time and memory difference between the two similar implementations?

Question

I was attempting the Leetcode Problem 239(Sliding Window Maximum).
Consider the two implementations, Sol1 and Sol2. Sol1:

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        deque<int> dq;
        vector<int> ans;
        for (int i=0; i<nums.size(); i++) {
            if (!dq.empty() && dq.back() == i-k) dq.pop_back();
            while (!dq.empty() && nums[dq.front()] < nums[i]) dq.pop_front();
            dq.push_front(i);
            if (i>=k-1) ans.push_back(nums[dq.back()]);
        }
        return ans;
    }
};

Sol2:

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        deque<int> dq;
        vector<int> ans;
        for (int i=0; i<nums.size(); i++) {
            if (!dq.empty() && dq.front() == i-k) dq.pop_front();
            while (!dq.empty() && nums[dq.back()] < nums[i]) dq.pop_back();
            dq.push_back(i);
            if (i>=k-1) ans.push_back(nums[dq.front()]);
        }
        return ans;
    }
};

Sol2 differs from Sol1 in these ways:

• The back() method of the deque has been changed to front() and vice versa.
• The push_front() method of the deque has been changed to push_back() and vice versa.
• The pop_front() method of the deque has been changed to pop_back() and vice versa. Logically, these two implementations are similar.

According to the C++ deque implementation,

The complexity (efficiency) of common operations on deques is as follows:

• Random access - constant O(1)
• Insertion or removal of elements at the end or beginning - constant O(1)
• Insertion or removal of elements - linear O(n)

But I observed a significant difference in the time and memory consumed by these implementations. I tried to check with few compilers, the differences are still there.

The results and the entire code used for testing can be found in this gist. Why is there a difference between the 2 implementations (Sol1 and Sol2)? There is also a difference when we use different compilers. I am not able to figure this out. Any help is appreciated.