Memory leak in Firefox with jQuery, AJAX, and HTML5 canvas

I'm polling my server using jQuery's ajax function and then using that data to update a canvas. I poll the server once each second (this is not done using setInterval(), in case you're wondering... I did hear that is sometimes the source of these issues. The canvas is animated, and I keep track of the frame rate. I use this data to figure out when a second has elapsed). This isn't an issue in Chrome, but in Firefox and Maxthon Cloud (and to a MUCH MUCH lesser degree Opera), performance gradually grows worse and worse. I think it's the ajax calls, and I have NO IDEA how to fix the issue. Here is my "callServer()" function, if that's of any use. Thanks!

function callServer(action, json)
{
    if(!json)
    {
        $.ajax({
            type: 'POST',
            url: 'okey.php.',
            data: 'action=' + action,
            cache: false,
            success: function(data)
            {
                switch(action)
                {
                    case 'ptv':
                        tilesValue = data;
                        break;
                    case 'ptc':
                        tilesColor = data;
                        break;
                    case 'tid':
                        //alert(data);
                        thisPlayerID = data;
                        break;
                    case 'pti':
                        playerTurnInfo = data;
                        //alert(data);
                        break;
                    case 'gs':
                        gameStatus = data;
                        break;
                    case 'steal':
                        alert(data);
                        break;
                    case 'draw':
                        alert(data);
                        break;
                    case 'testing':
                        alert(data);
                        break;
                }
            }
        });
    }
    else if(json)
    {
        $.ajax({
            type: 'POST',
            url: 'okey.php.',
            data: 'action=' + action,
            dataType: 'json',
            cache: false,
            success: function(data)
            {
                switch(action)
                {
                    case 'ptv':
                        tilesValue = data;
                        break;
                    case 'ptc':
                        tilesColor = data;
                        //alert(tilesColor.length);
                        break;
                    case 'pn':
                        playerNames = data;
                        break;
                    case 'pid':
                        playerIDs = data;
                        break;
                    case 'pts':
                        //alert("excellent");
                        turnStatuses = data;
                        break;
                    case 'ti':
                        tileIndeces = data;
                        //alert(tileIndeces.length)
                        break;
                    case 'dis':
                        //alert(parseInt(data[3]));
                        discarded = data;
                        //alert(parseInt(discarded[3]));
                        break;
                }
            }
        });
    }
}

Update: It is not the frequency of the calls that is causing the issue.